diff --git a/crates/load-cargo/src/lib.rs b/crates/load-cargo/src/lib.rs
index 33468a5003c3..8040a6f1888e 100644
--- a/crates/load-cargo/src/lib.rs
+++ b/crates/load-cargo/src/lib.rs
@@ -45,6 +45,7 @@ pub struct LoadCargoConfig {
     pub load_out_dirs_from_check: bool,
     pub with_proc_macro_server: ProcMacroServerChoice,
     pub prefill_caches: bool,
+    pub proc_macro_processes: usize,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -113,15 +114,25 @@ pub fn load_workspace_into_db(
     let proc_macro_server = match &load_config.with_proc_macro_server {
         ProcMacroServerChoice::Sysroot => ws.find_sysroot_proc_macro_srv().map(|it| {
             it.and_then(|it| {
-                ProcMacroClient::spawn(&it, extra_env, ws.toolchain.as_ref()).map_err(Into::into)
+                ProcMacroClient::spawn(
+                    &it,
+                    extra_env,
+                    ws.toolchain.as_ref(),
+                    load_config.proc_macro_processes,
+                )
+                .map_err(Into::into)
             })
             .map_err(|e| ProcMacroLoadingError::ProcMacroSrvError(e.to_string().into_boxed_str()))
         }),
-        ProcMacroServerChoice::Explicit(path) => {
-            Some(ProcMacroClient::spawn(path, extra_env, ws.toolchain.as_ref()).map_err(|e| {
-                ProcMacroLoadingError::ProcMacroSrvError(e.to_string().into_boxed_str())
-            }))
-        }
+        ProcMacroServerChoice::Explicit(path) => Some(
+            ProcMacroClient::spawn(
+                path,
+                extra_env,
+                ws.toolchain.as_ref(),
+                load_config.proc_macro_processes,
+            )
+            .map_err(|e| ProcMacroLoadingError::ProcMacroSrvError(e.to_string().into_boxed_str())),
+        ),
         ProcMacroServerChoice::None => Some(Err(ProcMacroLoadingError::Disabled)),
     };
     match &proc_macro_server {
@@ -435,7 +446,7 @@ pub fn load_proc_macro(
 ) -> ProcMacroLoadResult {
     let res: Result<Vec<_>, _> = (|| {
         let dylib = MacroDylib::new(path.to_path_buf());
-        let vec = server.load_dylib(dylib, Some(&mut reject_subrequests)).map_err(|e| {
+        let vec = server.load_dylib(dylib, Some(&reject_subrequests)).map_err(|e| {
             ProcMacroLoadingError::ProcMacroSrvError(format!("{e}").into_boxed_str())
         })?;
         if vec.is_empty() {
@@ -541,7 +552,7 @@ impl ProcMacroExpander for Expander {
         mixed_site: Span,
         current_dir: String,
     ) -> Result<tt::TopSubtree, ProcMacroExpansionError> {
-        let mut cb = |req| match req {
+        let cb = |req| match req {
             SubRequest::LocalFilePath { file_id } => {
                 let file_id = FileId::from_raw(file_id);
                 let source_root_id = db.file_source_root(file_id).source_root_id(db);
@@ -600,7 +611,7 @@ impl ProcMacroExpander for Expander {
             call_site,
             mixed_site,
             current_dir,
-            Some(&mut cb),
+            Some(&cb),
         ) {
             Ok(Ok(subtree)) => Ok(subtree),
             Ok(Err(err)) => Err(ProcMacroExpansionError::Panic(err)),
@@ -644,6 +655,7 @@ mod tests {
             load_out_dirs_from_check: false,
             with_proc_macro_server: ProcMacroServerChoice::None,
             prefill_caches: false,
+            proc_macro_processes: 1,
         };
         let (db, _vfs, _proc_macro) =
             load_workspace_at(path, &cargo_config, &load_cargo_config, &|_| {}).unwrap();
diff --git a/crates/proc-macro-api/src/bidirectional_protocol.rs b/crates/proc-macro-api/src/bidirectional_protocol.rs
index e44723a6a389..f23cc849d9ae 100644
--- a/crates/proc-macro-api/src/bidirectional_protocol.rs
+++ b/crates/proc-macro-api/src/bidirectional_protocol.rs
@@ -28,7 +28,7 @@ use crate::{
 
 pub mod msg;
 
-pub type SubCallback<'a> = &'a mut dyn FnMut(SubRequest) -> Result<SubResponse, ServerError>;
+pub type SubCallback<'a> = &'a dyn Fn(SubRequest) -> Result<SubResponse, ServerError>;
 
 pub fn run_conversation<C: Codec>(
     writer: &mut dyn Write,
@@ -138,6 +138,7 @@ pub(crate) fn find_proc_macros(
 
 pub(crate) fn expand(
     proc_macro: &ProcMacro,
+    process: &ProcMacroServerProcess,
     subtree: tt::SubtreeView<'_>,
     attr: Option<tt::SubtreeView<'_>>,
     env: Vec<(String, String)>,
@@ -147,7 +148,7 @@ pub(crate) fn expand(
     current_dir: String,
     callback: SubCallback<'_>,
 ) -> Result<Result<tt::TopSubtree, String>, crate::ServerError> {
-    let version = proc_macro.process.version();
+    let version = process.version();
     let mut span_data_table = SpanDataIndexMap::default();
     let def_site = span_data_table.insert_full(def_site).0;
     let call_site = span_data_table.insert_full(call_site).0;
@@ -164,7 +165,7 @@ pub(crate) fn expand(
                 call_site,
                 mixed_site,
             },
-            span_data_table: if proc_macro.process.rust_analyzer_spans() {
+            span_data_table: if process.rust_analyzer_spans() {
                 serialize_span_data_index_map(&span_data_table)
             } else {
                 Vec::new()
@@ -175,7 +176,7 @@ pub(crate) fn expand(
         current_dir: Some(current_dir),
     })));
 
-    let response_payload = run_request(&proc_macro.process, task, callback)?;
+    let response_payload = run_request(process, task, callback)?;
 
     match response_payload {
         BidirectionalMessage::Response(Response::ExpandMacro(it)) => Ok(it
diff --git a/crates/proc-macro-api/src/legacy_protocol.rs b/crates/proc-macro-api/src/legacy_protocol.rs
index 4524d1b66bfe..ab9a0316a21d 100644
--- a/crates/proc-macro-api/src/legacy_protocol.rs
+++ b/crates/proc-macro-api/src/legacy_protocol.rs
@@ -18,8 +18,7 @@ use crate::{
         flat::serialize_span_data_index_map,
     },
     process::ProcMacroServerProcess,
-    transport::codec::Codec,
-    transport::codec::{json::JsonProtocol, postcard::PostcardProtocol},
+    transport::codec::{Codec, json::JsonProtocol, postcard::PostcardProtocol},
     version,
 };
 
@@ -77,6 +76,7 @@ pub(crate) fn find_proc_macros(
 
 pub(crate) fn expand(
     proc_macro: &ProcMacro,
+    process: &ProcMacroServerProcess,
     subtree: tt::SubtreeView<'_>,
     attr: Option<tt::SubtreeView<'_>>,
     env: Vec<(String, String)>,
@@ -85,7 +85,7 @@ pub(crate) fn expand(
     mixed_site: Span,
     current_dir: String,
 ) -> Result<Result<tt::TopSubtree, String>, crate::ServerError> {
-    let version = proc_macro.process.version();
+    let version = process.version();
     let mut span_data_table = SpanDataIndexMap::default();
     let def_site = span_data_table.insert_full(def_site).0;
     let call_site = span_data_table.insert_full(call_site).0;
@@ -102,7 +102,7 @@ pub(crate) fn expand(
                 call_site,
                 mixed_site,
             },
-            span_data_table: if proc_macro.process.rust_analyzer_spans() {
+            span_data_table: if process.rust_analyzer_spans() {
                 serialize_span_data_index_map(&span_data_table)
             } else {
                 Vec::new()
@@ -113,7 +113,7 @@ pub(crate) fn expand(
         current_dir: Some(current_dir),
     };
 
-    let response = send_task(&proc_macro.process, Request::ExpandMacro(Box::new(task)))?;
+    let response = send_task(process, Request::ExpandMacro(Box::new(task)))?;
 
     match response {
         Response::ExpandMacro(it) => Ok(it
diff --git a/crates/proc-macro-api/src/lib.rs b/crates/proc-macro-api/src/lib.rs
index 98ee6817c2d2..016f27761c81 100644
--- a/crates/proc-macro-api/src/lib.rs
+++ b/crates/proc-macro-api/src/lib.rs
@@ -18,6 +18,7 @@ extern crate rustc_driver as _;
 
 pub mod bidirectional_protocol;
 pub mod legacy_protocol;
+pub mod pool;
 pub mod process;
 pub mod transport;
 
@@ -27,7 +28,9 @@ use span::{ErasedFileAstId, FIXUP_ERASED_FILE_AST_ID_MARKER, Span};
 use std::{fmt, io, sync::Arc, time::SystemTime};
 
 pub use crate::transport::codec::Codec;
-use crate::{bidirectional_protocol::SubCallback, process::ProcMacroServerProcess};
+use crate::{
+    bidirectional_protocol::SubCallback, pool::ProcMacroServerPool, process::ProcMacroServerProcess,
+};
 
 /// The versions of the server protocol
 pub mod version {
@@ -84,7 +87,7 @@ pub struct ProcMacroClient {
     ///
     /// That means that concurrent salsa requests may block each other when expanding proc macros,
     /// which is unfortunate, but simple and good enough for the time being.
-    process: Arc<ProcMacroServerProcess>,
+    pool: Arc<ProcMacroServerPool>,
     path: AbsPathBuf,
 }
 
@@ -106,7 +109,7 @@ impl MacroDylib {
 /// we share a single expander process for all macros within a workspace.
 #[derive(Debug, Clone)]
 pub struct ProcMacro {
-    process: Arc<ProcMacroServerProcess>,
+    pool: ProcMacroServerPool,
     dylib_path: Arc<AbsPathBuf>,
     name: Box<str>,
     kind: ProcMacroKind,
@@ -120,7 +123,6 @@ impl PartialEq for ProcMacro {
             && self.kind == other.kind
             && self.dylib_path == other.dylib_path
             && self.dylib_last_modified == other.dylib_last_modified
-            && Arc::ptr_eq(&self.process, &other.process)
     }
 }
 
@@ -150,9 +152,17 @@ impl ProcMacroClient {
             Item = (impl AsRef<std::ffi::OsStr>, &'a Option<impl 'a + AsRef<std::ffi::OsStr>>),
         > + Clone,
         version: Option<&Version>,
+        num_process: usize,
     ) -> io::Result<ProcMacroClient> {
-        let process = ProcMacroServerProcess::spawn(process_path, env, version)?;
-        Ok(ProcMacroClient { process: Arc::new(process), path: process_path.to_owned() })
+        let pool_size = num_process;
+        let mut workers = Vec::with_capacity(pool_size);
+        for _ in 0..pool_size {
+            let worker = ProcMacroServerProcess::spawn(process_path, env.clone(), version)?;
+            workers.push(worker);
+        }
+
+        let pool = ProcMacroServerPool::new(workers);
+        Ok(ProcMacroClient { pool: Arc::new(pool), path: process_path.to_owned() })
     }
 
     /// Invokes `spawn` and returns a client connected to the resulting read and write handles.
@@ -166,11 +176,20 @@ impl ProcMacroClient {
             Box<dyn process::ProcessExit>,
             Box<dyn io::Write + Send + Sync>,
             Box<dyn io::BufRead + Send + Sync>,
-        )>,
+        )> + Clone,
         version: Option<&Version>,
+        num_process: usize,
     ) -> io::Result<ProcMacroClient> {
-        let process = ProcMacroServerProcess::run(spawn, version, || "<unknown>".to_owned())?;
-        Ok(ProcMacroClient { process: Arc::new(process), path: process_path.to_owned() })
+        let pool_size = num_process;
+        let mut workers = Vec::with_capacity(pool_size);
+        for _ in 0..pool_size {
+            let worker =
+                ProcMacroServerProcess::run(spawn.clone(), version, || "<unknown>".to_owned())?;
+            workers.push(worker);
+        }
+
+        let pool = ProcMacroServerPool::new(workers);
+        Ok(ProcMacroClient { pool: Arc::new(pool), path: process_path.to_owned() })
     }
 
     /// Returns the absolute path to the proc-macro server.
@@ -184,31 +203,12 @@ impl ProcMacroClient {
         dylib: MacroDylib,
         callback: Option<SubCallback<'_>>,
     ) -> Result<Vec<ProcMacro>, ServerError> {
-        let _p = tracing::info_span!("ProcMacroServer::load_dylib").entered();
-        let macros = self.process.find_proc_macros(&dylib.path, callback)?;
-
-        let dylib_path = Arc::new(dylib.path);
-        let dylib_last_modified = std::fs::metadata(dylib_path.as_path())
-            .ok()
-            .and_then(|metadata| metadata.modified().ok());
-        match macros {
-            Ok(macros) => Ok(macros
-                .into_iter()
-                .map(|(name, kind)| ProcMacro {
-                    process: self.process.clone(),
-                    name: name.into(),
-                    kind,
-                    dylib_path: dylib_path.clone(),
-                    dylib_last_modified,
-                })
-                .collect()),
-            Err(message) => Err(ServerError { message, io: None }),
-        }
+        self.pool.load_dylib(&dylib, callback)
     }
 
     /// Checks if the proc-macro server has exited.
     pub fn exited(&self) -> Option<&ServerError> {
-        self.process.exited()
+        self.pool.exited()
     }
 }
 
@@ -224,7 +224,7 @@ impl ProcMacro {
     }
 
     fn needs_fixup_change(&self) -> bool {
-        let version = self.process.version();
+        let version = self.pool.version();
         (version::RUST_ANALYZER_SPAN_SUPPORT..version::HASHED_AST_ID).contains(&version)
     }
 
@@ -268,7 +268,7 @@ impl ProcMacro {
             }
         }
 
-        self.process.expand(
+        self.pool.pick_process()?.expand(
             self,
             subtree,
             attr,
diff --git a/crates/proc-macro-api/src/pool.rs b/crates/proc-macro-api/src/pool.rs
new file mode 100644
index 000000000000..a637bc0e480a
--- /dev/null
+++ b/crates/proc-macro-api/src/pool.rs
@@ -0,0 +1,91 @@
+//! A pool of proc-macro server processes
+use std::sync::Arc;
+
+use crate::{
+    MacroDylib, ProcMacro, ServerError, bidirectional_protocol::SubCallback,
+    process::ProcMacroServerProcess,
+};
+
+#[derive(Debug, Clone)]
+pub(crate) struct ProcMacroServerPool {
+    workers: Arc<[ProcMacroServerProcess]>,
+    version: u32,
+}
+
+impl ProcMacroServerPool {
+    pub(crate) fn new(workers: Vec<ProcMacroServerProcess>) -> Self {
+        let version = workers[0].version();
+        Self { workers: workers.into(), version }
+    }
+}
+
+impl ProcMacroServerPool {
+    pub(crate) fn exited(&self) -> Option<&ServerError> {
+        for worker in &*self.workers {
+            worker.exited()?;
+        }
+        self.workers[0].exited()
+    }
+
+    pub(crate) fn pick_process(&self) -> Result<&ProcMacroServerProcess, ServerError> {
+        let mut best: Option<&ProcMacroServerProcess> = None;
+        let mut best_load = u32::MAX;
+
+        for w in self.workers.iter().filter(|w| w.exited().is_none()) {
+            let load = w.number_of_active_req();
+
+            if load == 0 {
+                return Ok(w);
+            }
+
+            if load < best_load {
+                best = Some(w);
+                best_load = load;
+            }
+        }
+
+        best.ok_or_else(|| ServerError {
+            message: "all proc-macro server workers have exited".into(),
+            io: None,
+        })
+    }
+
+    pub(crate) fn load_dylib(
+        &self,
+        dylib: &MacroDylib,
+        callback: Option<SubCallback<'_>>,
+    ) -> Result<Vec<ProcMacro>, ServerError> {
+        let _span = tracing::info_span!("ProcMacroServer::load_dylib").entered();
+
+        let dylib_path = Arc::new(dylib.path.clone());
+        let dylib_last_modified =
+            std::fs::metadata(dylib_path.as_path()).ok().and_then(|m| m.modified().ok());
+
+        let (first, rest) = self.workers.split_first().expect("worker pool must not be empty");
+
+        let macros = first
+            .find_proc_macros(&dylib.path, callback)?
+            .map_err(|e| ServerError { message: e, io: None })?;
+
+        for worker in rest {
+            worker
+                .find_proc_macros(&dylib.path, callback)?
+                .map_err(|e| ServerError { message: e, io: None })?;
+        }
+
+        Ok(macros
+            .into_iter()
+            .map(|(name, kind)| ProcMacro {
+                pool: self.clone(),
+                name: name.into(),
+                kind,
+                dylib_path: dylib_path.clone(),
+                dylib_last_modified,
+            })
+            .collect())
+    }
+
+    pub(crate) fn version(&self) -> u32 {
+        self.version
+    }
+}
diff --git a/crates/proc-macro-api/src/process.rs b/crates/proc-macro-api/src/process.rs
index 4f8762158790..33caa9ada5bf 100644
--- a/crates/proc-macro-api/src/process.rs
+++ b/crates/proc-macro-api/src/process.rs
@@ -1,10 +1,14 @@
 //! Handle process life-time and message passing for proc-macro client
 
 use std::{
+    fmt::Debug,
     io::{self, BufRead, BufReader, Read, Write},
     panic::AssertUnwindSafe,
     process::{Child, ChildStdin, ChildStdout, Command, Stdio},
-    sync::{Arc, Mutex, OnceLock},
+    sync::{
+        Arc, Mutex, OnceLock,
+        atomic::{AtomicU32, Ordering},
+    },
 };
 
 use paths::AbsPath;
@@ -28,6 +32,7 @@ pub(crate) struct ProcMacroServerProcess {
     protocol: Protocol,
     /// Populated when the server exits.
     exited: OnceLock<AssertUnwindSafe<ServerError>>,
+    active: AtomicU32,
 }
 
 impl std::fmt::Debug for ProcMacroServerProcess {
@@ -75,7 +80,7 @@ impl ProcessExit for Process {
 }
 
 /// Maintains the state of the proc-macro server process.
-struct ProcessSrvState {
+pub(crate) struct ProcessSrvState {
     process: Box<dyn ProcessExit>,
     stdin: Box<dyn Write + Send + Sync>,
     stdout: Box<dyn BufRead + Send + Sync>,
@@ -163,11 +168,12 @@ impl ProcMacroServerProcess {
                         }
                     },
                     exited: OnceLock::new(),
+                    active: AtomicU32::new(0),
                 })
             };
             let mut srv = create_srv()?;
             tracing::info!("sending proc-macro server version check");
-            match srv.version_check(Some(&mut reject_subrequests)) {
+            match srv.version_check(Some(&reject_subrequests)) {
                 Ok(v) if v > version::CURRENT_API_VERSION => {
                     let process_version = binary_server_version();
                     err = Some(io::Error::other(format!(
@@ -181,7 +187,7 @@ impl ProcMacroServerProcess {
                     srv.version = v;
                     if srv.version >= version::RUST_ANALYZER_SPAN_SUPPORT
                         && let Ok(new_mode) =
-                            srv.enable_rust_analyzer_spans(Some(&mut reject_subrequests))
+                            srv.enable_rust_analyzer_spans(Some(&reject_subrequests))
                     {
                         match &mut srv.protocol {
                             Protocol::LegacyJson { mode }
@@ -203,6 +209,23 @@ impl ProcMacroServerProcess {
         Err(err.unwrap())
     }
 
+    /// Finds proc-macros in a given dynamic library.
+    pub(crate) fn find_proc_macros(
+        &self,
+        dylib_path: &AbsPath,
+        callback: Option<SubCallback<'_>>,
+    ) -> Result<Result<Vec<(String, ProcMacroKind)>, String>, ServerError> {
+        match self.protocol {
+            Protocol::LegacyJson { .. } | Protocol::LegacyPostcard { .. } => {
+                legacy_protocol::find_proc_macros(self, dylib_path)
+            }
+            Protocol::BidirectionalPostcardPrototype { .. } => {
+                let cb = callback.expect("callback required for bidirectional protocol");
+                bidirectional_protocol::find_proc_macros(self, dylib_path, cb)
+            }
+        }
+    }
+
     /// Returns the server error if the process has exited.
     pub(crate) fn exited(&self) -> Option<&ServerError> {
         self.exited.get().map(|it| &it.0)
@@ -255,23 +278,6 @@ impl ProcMacroServerProcess {
         }
     }
 
-    /// Finds proc-macros in a given dynamic library.
-    pub(crate) fn find_proc_macros(
-        &self,
-        dylib_path: &AbsPath,
-        callback: Option<SubCallback<'_>>,
-    ) -> Result<Result<Vec<(String, ProcMacroKind)>, String>, ServerError> {
-        match self.protocol {
-            Protocol::LegacyJson { .. } | Protocol::LegacyPostcard { .. } => {
-                legacy_protocol::find_proc_macros(self, dylib_path)
-            }
-            Protocol::BidirectionalPostcardPrototype { .. } => {
-                let cb = callback.expect("callback required for bidirectional protocol");
-                bidirectional_protocol::find_proc_macros(self, dylib_path, cb)
-            }
-        }
-    }
-
     pub(crate) fn expand(
         &self,
         proc_macro: &ProcMacro,
@@ -284,10 +290,12 @@ impl ProcMacroServerProcess {
         current_dir: String,
         callback: Option<SubCallback<'_>>,
     ) -> Result<Result<tt::TopSubtree, String>, ServerError> {
-        match self.protocol {
+        self.active.fetch_add(1, Ordering::AcqRel);
+        let result = match self.protocol {
             Protocol::LegacyJson { .. } | Protocol::LegacyPostcard { .. } => {
                 legacy_protocol::expand(
                     proc_macro,
+                    self,
                     subtree,
                     attr,
                     env,
@@ -299,6 +307,7 @@ impl ProcMacroServerProcess {
             }
             Protocol::BidirectionalPostcardPrototype { .. } => bidirectional_protocol::expand(
                 proc_macro,
+                self,
                 subtree,
                 attr,
                 env,
@@ -308,7 +317,10 @@ impl ProcMacroServerProcess {
                 current_dir,
                 callback.expect("callback required for bidirectional protocol"),
             ),
-        }
+        };
+
+        self.active.fetch_sub(1, Ordering::AcqRel);
+        result
     }
 
     pub(crate) fn send_task<Request, Response, C: Codec>(
@@ -367,6 +379,10 @@ impl ProcMacroServerProcess {
             bidirectional_protocol::run_conversation::<C>(writer, reader, buf, initial, callback)
         })
     }
+
+    pub(crate) fn number_of_active_req(&self) -> u32 {
+        self.active.load(Ordering::Acquire)
+    }
 }
 
 /// Manages the execution of the proc-macro server process.
diff --git a/crates/rust-analyzer/src/cli/analysis_stats.rs b/crates/rust-analyzer/src/cli/analysis_stats.rs
index a02d1a78564f..1995d3889891 100644
--- a/crates/rust-analyzer/src/cli/analysis_stats.rs
+++ b/crates/rust-analyzer/src/cli/analysis_stats.rs
@@ -91,6 +91,7 @@ impl flags::AnalysisStats {
                 }
             },
             prefill_caches: false,
+            proc_macro_processes: 1,
         };
 
         let build_scripts_time = if self.disable_build_scripts {
diff --git a/crates/rust-analyzer/src/cli/diagnostics.rs b/crates/rust-analyzer/src/cli/diagnostics.rs
index 776069f155f0..575c77f8428c 100644
--- a/crates/rust-analyzer/src/cli/diagnostics.rs
+++ b/crates/rust-analyzer/src/cli/diagnostics.rs
@@ -41,6 +41,7 @@ impl flags::Diagnostics {
             load_out_dirs_from_check: !self.disable_build_scripts,
             with_proc_macro_server,
             prefill_caches: false,
+            proc_macro_processes: 1,
         };
         let (db, _vfs, _proc_macro) =
             load_workspace_at(&self.path, &cargo_config, &load_cargo_config, &|_| {})?;
diff --git a/crates/rust-analyzer/src/cli/lsif.rs b/crates/rust-analyzer/src/cli/lsif.rs
index f3b0699d5515..e5e238db6361 100644
--- a/crates/rust-analyzer/src/cli/lsif.rs
+++ b/crates/rust-analyzer/src/cli/lsif.rs
@@ -293,6 +293,7 @@ impl flags::Lsif {
             load_out_dirs_from_check: true,
             with_proc_macro_server: ProcMacroServerChoice::Sysroot,
             prefill_caches: false,
+            proc_macro_processes: 1,
         };
         let path = AbsPathBuf::assert_utf8(env::current_dir()?.join(self.path));
         let root = ProjectManifest::discover_single(&path)?;
diff --git a/crates/rust-analyzer/src/cli/prime_caches.rs b/crates/rust-analyzer/src/cli/prime_caches.rs
index 467d8a53884a..d5da6791797b 100644
--- a/crates/rust-analyzer/src/cli/prime_caches.rs
+++ b/crates/rust-analyzer/src/cli/prime_caches.rs
@@ -38,6 +38,7 @@ impl flags::PrimeCaches {
             // we want to ensure that this command, not `load_workspace_at`,
             // is responsible for that work.
             prefill_caches: false,
+            proc_macro_processes: config.proc_macro_num_processes(),
         };
 
         let root = AbsPathBuf::assert_utf8(std::env::current_dir()?.join(root));
diff --git a/crates/rust-analyzer/src/cli/run_tests.rs b/crates/rust-analyzer/src/cli/run_tests.rs
index 82ace8c8b315..d4a56d773e7d 100644
--- a/crates/rust-analyzer/src/cli/run_tests.rs
+++ b/crates/rust-analyzer/src/cli/run_tests.rs
@@ -23,6 +23,7 @@ impl flags::RunTests {
             load_out_dirs_from_check: true,
             with_proc_macro_server: ProcMacroServerChoice::Sysroot,
             prefill_caches: false,
+            proc_macro_processes: 1,
         };
         let (ref db, _vfs, _proc_macro) =
             load_workspace_at(&self.path, &cargo_config, &load_cargo_config, &|_| {})?;
diff --git a/crates/rust-analyzer/src/cli/rustc_tests.rs b/crates/rust-analyzer/src/cli/rustc_tests.rs
index 249566d2ac16..e8c6c5f4d4f7 100644
--- a/crates/rust-analyzer/src/cli/rustc_tests.rs
+++ b/crates/rust-analyzer/src/cli/rustc_tests.rs
@@ -103,6 +103,7 @@ impl Tester {
             load_out_dirs_from_check: false,
             with_proc_macro_server: ProcMacroServerChoice::Sysroot,
             prefill_caches: false,
+            proc_macro_processes: 1,
         };
         let (db, _vfs, _proc_macro) =
             load_workspace(workspace, &cargo_config.extra_env, &load_cargo_config)?;
diff --git a/crates/rust-analyzer/src/cli/scip.rs b/crates/rust-analyzer/src/cli/scip.rs
index 271d2507bcfe..ed0476697c9c 100644
--- a/crates/rust-analyzer/src/cli/scip.rs
+++ b/crates/rust-analyzer/src/cli/scip.rs
@@ -52,6 +52,7 @@ impl flags::Scip {
             load_out_dirs_from_check: true,
             with_proc_macro_server: ProcMacroServerChoice::Sysroot,
             prefill_caches: true,
+            proc_macro_processes: config.proc_macro_num_processes(),
         };
         let cargo_config = config.cargo(None);
         let (db, vfs, _) = load_workspace_at(
diff --git a/crates/rust-analyzer/src/cli/ssr.rs b/crates/rust-analyzer/src/cli/ssr.rs
index 39186831459c..5c69bda723fb 100644
--- a/crates/rust-analyzer/src/cli/ssr.rs
+++ b/crates/rust-analyzer/src/cli/ssr.rs
@@ -20,6 +20,7 @@ impl flags::Ssr {
             load_out_dirs_from_check: true,
             with_proc_macro_server: ProcMacroServerChoice::Sysroot,
             prefill_caches: false,
+            proc_macro_processes: 1,
         };
         let (ref db, vfs, _proc_macro) = load_workspace_at(
             &std::env::current_dir()?,
@@ -56,6 +57,7 @@ impl flags::Search {
             load_out_dirs_from_check: true,
             with_proc_macro_server: ProcMacroServerChoice::Sysroot,
             prefill_caches: false,
+            proc_macro_processes: 1,
         };
         let (ref db, _vfs, _proc_macro) = load_workspace_at(
             &std::env::current_dir()?,
diff --git a/crates/rust-analyzer/src/cli/unresolved_references.rs b/crates/rust-analyzer/src/cli/unresolved_references.rs
index 294add682d01..49c6fcb91ebf 100644
--- a/crates/rust-analyzer/src/cli/unresolved_references.rs
+++ b/crates/rust-analyzer/src/cli/unresolved_references.rs
@@ -44,6 +44,7 @@ impl flags::UnresolvedReferences {
             load_out_dirs_from_check: !self.disable_build_scripts,
             with_proc_macro_server,
             prefill_caches: false,
+            proc_macro_processes: config.proc_macro_num_processes(),
         };
         let (db, vfs, _proc_macro) =
             load_workspace_at(&self.path, &cargo_config, &load_cargo_config, &|_| {})?;
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index 28ac94e4deb6..98495f6150da 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -387,6 +387,12 @@ config_data! {
         /// Enable support for procedural macros, implies `#rust-analyzer.cargo.buildScripts.enable#`.
         procMacro_enable: bool = true,
 
+        /// Number of proc-macro server processes to spawn.
+        ///
+        /// Controls how many independent `proc-macro-srv` processes rust-analyzer
+        /// runs in parallel to handle macro expansion.
+        procMacro_processes: NumProcesses = NumProcesses::Concrete(1),
+
         /// Internal config, path to proc-macro server executable.
         procMacro_server: Option<Utf8PathBuf> = None,
 
@@ -2641,6 +2647,13 @@ impl Config {
         }
     }
 
+    pub fn proc_macro_num_processes(&self) -> usize {
+        match self.procMacro_processes() {
+            NumProcesses::Concrete(0) | NumProcesses::Physical => num_cpus::get_physical(),
+            &NumProcesses::Concrete(n) => n,
+        }
+    }
+
     pub fn main_loop_num_threads(&self) -> usize {
         match self.numThreads() {
             Some(NumThreads::Concrete(0)) | None | Some(NumThreads::Physical) => {
@@ -3077,6 +3090,14 @@ pub enum NumThreads {
     Concrete(usize),
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum NumProcesses {
+    Physical,
+    #[serde(untagged)]
+    Concrete(usize),
+}
+
 macro_rules! _default_val {
     ($default:expr, $ty:ty) => {{
         let default_: $ty = $default;
@@ -3903,6 +3924,22 @@ fn field_props(field: &str, ty: &str, doc: &[&str], default: &str) -> serde_json
                 },
             ],
         },
+        "NumProcesses" => set! {
+            "anyOf": [
+                {
+                    "type": "number",
+                    "minimum": 0,
+                    "maximum": 255
+                },
+                {
+                    "type": "string",
+                    "enum": ["physical"],
+                    "enumDescriptions": [
+                        "Use the number of physical cores",
+                    ],
+                },
+            ],
+        },
         "Option<NumThreads>" => set! {
             "anyOf": [
                 {
diff --git a/crates/rust-analyzer/src/integrated_benchmarks.rs b/crates/rust-analyzer/src/integrated_benchmarks.rs
index c61825b99fec..d16ca2fb48ac 100644
--- a/crates/rust-analyzer/src/integrated_benchmarks.rs
+++ b/crates/rust-analyzer/src/integrated_benchmarks.rs
@@ -53,6 +53,7 @@ fn integrated_highlighting_benchmark() {
         load_out_dirs_from_check: true,
         with_proc_macro_server: ProcMacroServerChoice::Sysroot,
         prefill_caches: false,
+        proc_macro_processes: 1,
     };
 
     let (db, vfs, _proc_macro) = {
@@ -121,6 +122,7 @@ fn integrated_completion_benchmark() {
         load_out_dirs_from_check: true,
         with_proc_macro_server: ProcMacroServerChoice::Sysroot,
         prefill_caches: true,
+        proc_macro_processes: 1,
     };
 
     let (db, vfs, _proc_macro) = {
@@ -322,6 +324,7 @@ fn integrated_diagnostics_benchmark() {
         load_out_dirs_from_check: true,
         with_proc_macro_server: ProcMacroServerChoice::Sysroot,
         prefill_caches: true,
+        proc_macro_processes: 1,
     };
 
     let (db, vfs, _proc_macro) = {
diff --git a/crates/rust-analyzer/src/reload.rs b/crates/rust-analyzer/src/reload.rs
index ccafbd7b30b9..83f4a19b39fa 100644
--- a/crates/rust-analyzer/src/reload.rs
+++ b/crates/rust-analyzer/src/reload.rs
@@ -701,15 +701,19 @@ impl GlobalState {
                     _ => Default::default(),
                 };
                 info!("Using proc-macro server at {path}");
+                let num_process = self.config.proc_macro_num_processes();
 
-                Some(ProcMacroClient::spawn(&path, &env, ws.toolchain.as_ref()).map_err(|err| {
-                    tracing::error!(
-                        "Failed to run proc-macro server from path {path}, error: {err:?}",
-                    );
-                    anyhow::format_err!(
-                        "Failed to run proc-macro server from path {path}, error: {err:?}",
-                    )
-                }))
+                Some(
+                    ProcMacroClient::spawn(&path, &env, ws.toolchain.as_ref(), num_process)
+                        .map_err(|err| {
+                            tracing::error!(
+                                "Failed to run proc-macro server from path {path}, error: {err:?}",
+                            );
+                            anyhow::format_err!(
+                                "Failed to run proc-macro server from path {path}, error: {err:?}",
+                            )
+                        }),
+                )
             }))
         }
 
diff --git a/docs/book/src/configuration_generated.md b/docs/book/src/configuration_generated.md
index c4124aaae075..5b1a2e111196 100644
--- a/docs/book/src/configuration_generated.md
+++ b/docs/book/src/configuration_generated.md
@@ -1318,6 +1318,16 @@ These proc-macros will be ignored when trying to expand them.
 This config takes a map of crate names with the exported proc-macro names to ignore as values.
 
 
+## rust-analyzer.procMacro.processes {#procMacro.processes}
+
+Default: `1`
+
+Number of proc-macro server processes to spawn.
+
+Controls how many independent `proc-macro-srv` processes rust-analyzer
+runs in parallel to handle macro expansion.
+
+
 ## rust-analyzer.procMacro.server {#procMacro.server}
 
 Default: `null`
diff --git a/editors/code/package.json b/editors/code/package.json
index 0d91378706a4..406e41767f6d 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -2770,6 +2770,31 @@
                     }
                 }
             },
+            {
+                "title": "Proc Macro",
+                "properties": {
+                    "rust-analyzer.procMacro.processes": {
+                        "markdownDescription": "Number of proc-macro server processes to spawn.\n\nControls how many independent `proc-macro-srv` processes rust-analyzer\nruns in parallel to handle macro expansion.",
+                        "default": 1,
+                        "anyOf": [
+                            {
+                                "type": "number",
+                                "minimum": 0,
+                                "maximum": 255
+                            },
+                            {
+                                "type": "string",
+                                "enum": [
+                                    "physical"
+                                ],
+                                "enumDescriptions": [
+                                    "Use the number of physical cores"
+                                ]
+                            }
+                        ]
+                    }
+                }
+            },
             {
                 "title": "Proc Macro",
                 "properties": {