diff --git a/backend/src/server/plugins/auth/inject-identity.ts b/backend/src/server/plugins/auth/inject-identity.ts
index 69f3b953d64..961d05b36f9 100644
--- a/backend/src/server/plugins/auth/inject-identity.ts
+++ b/backend/src/server/plugins/auth/inject-identity.ts
@@ -130,6 +130,19 @@ export const injectIdentity = fp(
   async (server: FastifyZodProvider, opt: { shouldForwardWritesToPrimaryInstance?: boolean }) => {
     server.decorateRequest("auth", null);
     server.decorateRequest("shouldForwardWritesToPrimaryInstance", Boolean(opt.shouldForwardWritesToPrimaryInstance));
+
+    // Hoisted outside onRequest hook to avoid per-request function allocation on this hot path
+    const fireIdentifyForUser = (user: TUsers) => {
+      const distinctId = user.username ?? user.email ?? "";
+      if (distinctId) {
+        void server.services.telemetry.identifyUser(distinctId, {
+          email: user.email ?? undefined,
+          username: user.username,
+          userId: user.id
+        });
+      }
+    };
+
     server.addHook("onRequest", async (req) => {
       const appCfg = getConfig();
 
@@ -184,6 +197,7 @@ export const injectIdentity = fp(
             isMfaVerified: token.isMfaVerified,
             token
           };
+          fireIdentifyForUser(user);
           break;
         }
         case AuthMode.MCP_JWT: {
@@ -205,6 +219,7 @@ export const injectIdentity = fp(
             isMfaVerified: token.isMfaVerified,
             token
           };
+          fireIdentifyForUser(user);
           break;
         }
         case AuthMode.IDENTITY_ACCESS_TOKEN: {
diff --git a/backend/src/server/routes/v1/admin-router.ts b/backend/src/server/routes/v1/admin-router.ts
index fe9274b7f3c..59b706f0947 100644
--- a/backend/src/server/routes/v1/admin-router.ts
+++ b/backend/src/server/routes/v1/admin-router.ts
@@ -643,14 +643,18 @@ export const registerAdminRouter = async (server: FastifyZodProvider) => {
 
       const adminDistinctId = user.user.username ?? user.user.email ?? "";
       if (adminDistinctId) {
-        void server.services.telemetry.identifyUser(adminDistinctId, {
-          email: user.user.email ?? undefined,
-          username: user.user.username,
-          userId: user.user.id,
-          firstName: user.user.firstName ?? undefined,
-          lastName: user.user.lastName ?? undefined,
-          superAdmin: true
-        });
+        void server.services.telemetry.identifyUser(
+          adminDistinctId,
+          {
+            email: user.user.email ?? undefined,
+            username: user.user.username,
+            userId: user.user.id,
+            firstName: user.user.firstName ?? undefined,
+            lastName: user.user.lastName ?? undefined,
+            superAdmin: true
+          },
+          { skipDedup: true }
+        );
       }
 
       void res.setCookie("jid", token.refresh, {
@@ -804,14 +808,18 @@ export const registerAdminRouter = async (server: FastifyZodProvider) => {
 
       const bootstrapDistinctId = user.user.username ?? user.user.email ?? "";
       if (bootstrapDistinctId) {
-        void server.services.telemetry.identifyUser(bootstrapDistinctId, {
-          email: user.user.email ?? undefined,
-          username: user.user.username,
-          userId: user.user.id,
-          firstName: user.user.firstName ?? undefined,
-          lastName: user.user.lastName ?? undefined,
-          superAdmin: true
-        });
+        void server.services.telemetry.identifyUser(
+          bootstrapDistinctId,
+          {
+            email: user.user.email ?? undefined,
+            username: user.user.username,
+            userId: user.user.id,
+            firstName: user.user.firstName ?? undefined,
+            lastName: user.user.lastName ?? undefined,
+            superAdmin: true
+          },
+          { skipDedup: true }
+        );
       }
 
       return {
diff --git a/backend/src/server/routes/v1/sso-router.ts b/backend/src/server/routes/v1/sso-router.ts
index e9ffbad269b..bd5c92080d7 100644
--- a/backend/src/server/routes/v1/sso-router.ts
+++ b/backend/src/server/routes/v1/sso-router.ts
@@ -79,13 +79,17 @@ export const registerOauthMiddlewares = (server: FastifyZodProvider) => {
 
             const googleDistinctId = user.username ?? user.email ?? "";
             if (googleDistinctId) {
-              void server.services.telemetry.identifyUser(googleDistinctId, {
-                email: user.email ?? undefined,
-                username: user.username,
-                userId: user.id,
-                firstName: user.firstName ?? undefined,
-                lastName: user.lastName ?? undefined
-              });
+              void server.services.telemetry.identifyUser(
+                googleDistinctId,
+                {
+                  email: user.email ?? undefined,
+                  username: user.username,
+                  userId: user.id,
+                  firstName: user.firstName ?? undefined,
+                  lastName: user.lastName ?? undefined
+                },
+                { skipDedup: true }
+              );
             }
 
             if (appCfg.OTEL_TELEMETRY_COLLECTION_ENABLED) {
@@ -162,13 +166,17 @@ export const registerOauthMiddlewares = (server: FastifyZodProvider) => {
 
             const githubDistinctId = user.username ?? user.email ?? "";
             if (githubDistinctId) {
-              void server.services.telemetry.identifyUser(githubDistinctId, {
-                email: user.email ?? undefined,
-                username: user.username,
-                userId: user.id,
-                firstName: user.firstName ?? undefined,
-                lastName: user.lastName ?? undefined
-              });
+              void server.services.telemetry.identifyUser(
+                githubDistinctId,
+                {
+                  email: user.email ?? undefined,
+                  username: user.username,
+                  userId: user.id,
+                  firstName: user.firstName ?? undefined,
+                  lastName: user.lastName ?? undefined
+                },
+                { skipDedup: true }
+              );
             }
 
             if (appCfg.OTEL_TELEMETRY_COLLECTION_ENABLED) {
@@ -237,13 +245,17 @@ export const registerOauthMiddlewares = (server: FastifyZodProvider) => {
 
             const gitlabDistinctId = user.username ?? user.email ?? "";
             if (gitlabDistinctId) {
-              void server.services.telemetry.identifyUser(gitlabDistinctId, {
-                email: user.email ?? undefined,
-                username: user.username,
-                userId: user.id,
-                firstName: user.firstName ?? undefined,
-                lastName: user.lastName ?? undefined
-              });
+              void server.services.telemetry.identifyUser(
+                gitlabDistinctId,
+                {
+                  email: user.email ?? undefined,
+                  username: user.username,
+                  userId: user.id,
+                  firstName: user.firstName ?? undefined,
+                  lastName: user.lastName ?? undefined
+                },
+                { skipDedup: true }
+              );
             }
 
             if (appCfg.OTEL_TELEMETRY_COLLECTION_ENABLED) {
@@ -593,11 +605,15 @@ export const registerSsoRouter = async (server: FastifyZodProvider) => {
 
       const tokenExchangeDistinctId = data.user.username ?? data.user.email ?? "";
       if (tokenExchangeDistinctId) {
-        void server.services.telemetry.identifyUser(tokenExchangeDistinctId, {
-          email: data.user.email ?? undefined,
-          username: data.user.username,
-          userId: data.user.userId
-        });
+        void server.services.telemetry.identifyUser(
+          tokenExchangeDistinctId,
+          {
+            email: data.user.email ?? undefined,
+            username: data.user.username,
+            userId: data.user.userId
+          },
+          { skipDedup: true }
+        );
       }
 
       if ([AuthMethod.GOOGLE, AuthMethod.GITHUB, AuthMethod.GITLAB].includes(data.decodedProviderToken.authMethod)) {
diff --git a/backend/src/server/routes/v3/login-router.ts b/backend/src/server/routes/v3/login-router.ts
index aea8883a697..05cc17352a3 100644
--- a/backend/src/server/routes/v3/login-router.ts
+++ b/backend/src/server/routes/v3/login-router.ts
@@ -157,11 +157,15 @@ export const registerLoginRouter = async (server: FastifyZodProvider) => {
 
       const login2DistinctId = data.user.username ?? data.user.email ?? "";
       if (login2DistinctId) {
-        void server.services.telemetry.identifyUser(login2DistinctId, {
-          email: data.user.email ?? undefined,
-          username: data.user.username,
-          userId: data.user.userId
-        });
+        void server.services.telemetry.identifyUser(
+          login2DistinctId,
+          {
+            email: data.user.email ?? undefined,
+            username: data.user.username,
+            userId: data.user.userId
+          },
+          { skipDedup: true }
+        );
       }
 
       void res.setCookie("jid", data.token.refresh, {
@@ -232,11 +236,15 @@ export const registerLoginRouter = async (server: FastifyZodProvider) => {
 
       const loginDistinctId = user.username ?? user.email ?? "";
       if (loginDistinctId) {
-        void server.services.telemetry.identifyUser(loginDistinctId, {
-          email: user.email ?? undefined,
-          username: user.username,
-          userId: user.userId
-        });
+        void server.services.telemetry.identifyUser(
+          loginDistinctId,
+          {
+            email: user.email ?? undefined,
+            username: user.username,
+            userId: user.userId
+          },
+          { skipDedup: true }
+        );
       }
 
       void res.setCookie("jid", tokens.refreshToken, {
diff --git a/backend/src/server/routes/v3/signup-router.ts b/backend/src/server/routes/v3/signup-router.ts
index 1793b5e2257..1b6ad4b4a18 100644
--- a/backend/src/server/routes/v3/signup-router.ts
+++ b/backend/src/server/routes/v3/signup-router.ts
@@ -160,16 +160,20 @@ export const registerSignupRouter = async (server: FastifyZodProvider) => {
 
       const signupDistinctId = user.username ?? user.email ?? "";
       if (signupDistinctId) {
-        void server.services.telemetry.identifyUser(signupDistinctId, {
-          email: user.email ?? undefined,
-          username: user.username,
-          userId: user.id,
-          firstName: user.firstName ?? undefined,
-          lastName: user.lastName ?? undefined,
-          isEmailVerified: user.isEmailVerified ?? undefined,
-          isMfaEnabled: user.isMfaEnabled ?? undefined,
-          superAdmin: user.superAdmin ?? undefined
-        });
+        void server.services.telemetry.identifyUser(
+          signupDistinctId,
+          {
+            email: user.email ?? undefined,
+            username: user.username,
+            userId: user.id,
+            firstName: user.firstName ?? undefined,
+            lastName: user.lastName ?? undefined,
+            isEmailVerified: user.isEmailVerified ?? undefined,
+            isMfaEnabled: user.isMfaEnabled ?? undefined,
+            superAdmin: user.superAdmin ?? undefined
+          },
+          { skipDedup: true }
+        );
       }
 
       void res.setCookie("jid", refreshToken, {
@@ -236,16 +240,20 @@ export const registerSignupRouter = async (server: FastifyZodProvider) => {
 
       const inviteDistinctId = user.username ?? user.email ?? "";
       if (inviteDistinctId) {
-        void server.services.telemetry.identifyUser(inviteDistinctId, {
-          email: user.email ?? undefined,
-          username: user.username,
-          userId: user.id,
-          firstName: user.firstName ?? undefined,
-          lastName: user.lastName ?? undefined,
-          isEmailVerified: user.isEmailVerified ?? undefined,
-          isMfaEnabled: user.isMfaEnabled ?? undefined,
-          superAdmin: user.superAdmin ?? undefined
-        });
+        void server.services.telemetry.identifyUser(
+          inviteDistinctId,
+          {
+            email: user.email ?? undefined,
+            username: user.username,
+            userId: user.id,
+            firstName: user.firstName ?? undefined,
+            lastName: user.lastName ?? undefined,
+            isEmailVerified: user.isEmailVerified ?? undefined,
+            isMfaEnabled: user.isMfaEnabled ?? undefined,
+            superAdmin: user.superAdmin ?? undefined
+          },
+          { skipDedup: true }
+        );
       }
 
       void res.setCookie("jid", refreshToken, {
diff --git a/backend/src/services/telemetry/telemetry-service.ts b/backend/src/services/telemetry/telemetry-service.ts
index 8a681e3d43a..644e2d863e2 100644
--- a/backend/src/services/telemetry/telemetry-service.ts
+++ b/backend/src/services/telemetry/telemetry-service.ts
@@ -371,7 +371,13 @@ To opt into telemetry, you can set "TELEMETRY_ENABLED=true" within the environme
     }
   };
 
-  const identifyUser = (
+  const TELEMETRY_IDENTIFY_CACHE_KEY_PREFIX = "telemetry-identify";
+  const TELEMETRY_IDENTIFY_CACHE_TTL = 600; // 10 minutes
+
+  // In-memory fallback dedup set to limit blast radius during Redis outages
+  const inMemoryIdentifyDedup = new Set<string>();
+
+  const identifyUser = async (
     distinctId: string,
     properties: {
       email?: string;
@@ -382,12 +388,35 @@ To opt into telemetry, you can set "TELEMETRY_ENABLED=true" within the environme
       isMfaEnabled?: boolean;
       isEmailVerified?: boolean;
       superAdmin?: boolean;
-    }
+    },
+    { skipDedup }: { skipDedup?: boolean } = {}
   ) => {
     if (postHog && distinctId) {
       const instanceType = licenseService.getInstanceType();
       if (instanceType === InstanceType.Cloud) {
-        postHog.identify({ distinctId, properties });
+        if (!skipDedup) {
+          try {
+            const cacheKey = `${TELEMETRY_IDENTIFY_CACHE_KEY_PREFIX}:${distinctId}`;
+            // Atomic SET NX + EX: only the first caller within the TTL window proceeds
+            const wasSet = await keyStore.setItemWithExpiryNX(cacheKey, TELEMETRY_IDENTIFY_CACHE_TTL, "1");
+            if (!wasSet) return;
+          } catch (error) {
+            logger.error(error, `Failed to check PostHog identify dedup cache for distinctId=${distinctId}`);
+            // In-memory fallback to limit blast radius during Redis outage
+            if (inMemoryIdentifyDedup.has(distinctId)) return;
+            inMemoryIdentifyDedup.add(distinctId);
+            const timer = setTimeout(
+              () => inMemoryIdentifyDedup.delete(distinctId),
+              TELEMETRY_IDENTIFY_CACHE_TTL * 1000
+            );
+            timer.unref();
+          }
+        }
+        try {
+          postHog.identify({ distinctId, properties });
+        } catch (err) {
+          logger.error(err, `Failed to call postHog.identify for distinctId=${distinctId}`);
+        }
       }
     }
   };