diff --git a/klippy/chelper/c_helper.so b/klippy/chelper/c_helper.so
index b4db819de326..2ae3ff2f58da 100755
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diff --git a/klippy/chelper/itersolve.o b/klippy/chelper/itersolve.o
index 53ec524b80a6..c18e24fcf5e6 100644
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diff --git a/klippy/chelper/kin_cartesian.o b/klippy/chelper/kin_cartesian.o
index f7d2661ebb6a..17d44f43cb56 100644
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diff --git a/klippy/chelper/kin_corexy.o b/klippy/chelper/kin_corexy.o
index 1a37d0a75cf6..5a1f6034c174 100644
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diff --git a/klippy/chelper/kin_corexz.o b/klippy/chelper/kin_corexz.o
index d1f0ca67eb95..435a9f8b737b 100644
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diff --git a/klippy/chelper/kin_delta.o b/klippy/chelper/kin_delta.o
index dedff9dea5f9..eff926d79f54 100644
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diff --git a/klippy/chelper/kin_deltesian.o b/klippy/chelper/kin_deltesian.o
index 84cf5c5ea100..543d34a87f62 100644
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diff --git a/klippy/chelper/kin_extruder.o b/klippy/chelper/kin_extruder.o
index 4394e98e35db..e35b3ef712ce 100644
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diff --git a/klippy/chelper/kin_idex.o b/klippy/chelper/kin_idex.o
index 5ed48c864a09..424e83576018 100644
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diff --git a/klippy/chelper/kin_polar.o b/klippy/chelper/kin_polar.o
index ebe32bd1c30d..10e536ceb4ad 100644
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diff --git a/klippy/chelper/kin_rotary_delta.o b/klippy/chelper/kin_rotary_delta.o
index e12d76404c82..12361a202569 100644
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diff --git a/klippy/chelper/kin_shaper.o b/klippy/chelper/kin_shaper.o
index 85309d041476..3b52b0ac3e77 100644
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diff --git a/klippy/chelper/kin_winch.o b/klippy/chelper/kin_winch.o
index e290621bce7f..39d6f4892349 100644
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diff --git a/klippy/chelper/msgblock.o b/klippy/chelper/msgblock.o
index 401695a41fbb..0beb7f9c5f46 100644
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diff --git a/klippy/chelper/pollreactor.o b/klippy/chelper/pollreactor.o
index 4d7b56ee6ea9..7d88a70457d3 100644
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diff --git a/klippy/chelper/pyhelper.o b/klippy/chelper/pyhelper.o
index df6e839106d3..0e653c0d3a47 100644
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diff --git a/klippy/chelper/serialqueue.c b/klippy/chelper/serialqueue.c
index c207495cdc6c..8f3cbb9aef43 100644
--- a/klippy/chelper/serialqueue.c
+++ b/klippy/chelper/serialqueue.c
@@ -612,6 +612,7 @@ static void *
 background_thread(void *data)
 {
     struct serialqueue *sq = data;
+    nice(-20);
     pollreactor_run(sq->pr);
 
     pthread_mutex_lock(&sq->lock);
diff --git a/klippy/chelper/serialqueue.o b/klippy/chelper/serialqueue.o
index 5260ef7c07a6..019f86356f7a 100644
Binary files a/klippy/chelper/serialqueue.o and b/klippy/chelper/serialqueue.o differ
diff --git a/klippy/chelper/stepcompress.c b/klippy/chelper/stepcompress.c
index 310f2bf31f64..8bfc330ab394 100644
--- a/klippy/chelper/stepcompress.c
+++ b/klippy/chelper/stepcompress.c
@@ -211,6 +211,17 @@ check_line(struct stepcompress *sc, struct step_move move)
         || move.interval >= 0x80000000) {
         errorf("stepcompress o=%d i=%d c=%d a=%d: Invalid sequence"
                , sc->oid, move.interval, move.count, move.add);
+        errorf("stepcompress queue[%p]=%u queue_end[%p]=%u queue_pos[%p]=%u queue_next[%p]=%u last_step_clock=%llu max_error=%u : lxc check_line"
+               , sc->queue, *(sc->queue), sc->queue_end, *(sc->queue_end), sc->queue_pos, *(sc->queue_pos),
+               sc->queue_next, *(sc->queue_next), sc->last_step_clock, sc->max_error);
+        uint16_t i;
+        uint32_t intervals = move.interval, ps = 0;
+        for (i=0; i<move.count; i++) {
+            ps += intervals;
+            struct points points = minmax_point(sc, sc->queue_pos + i);
+            errorf("stepcompress queue_pos+i=%u ps=%u minp=%u maxp=%u : lxc Invalid sequence 2"
+               , *(sc->queue_pos + i), ps, points.minp, points.maxp);
+        }
         return ERROR_RET;
     }
     uint32_t interval = move.interval, p = 0;
diff --git a/klippy/chelper/stepcompress.o b/klippy/chelper/stepcompress.o
index ae75ab6dc23d..1ded68865918 100644
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diff --git a/klippy/chelper/trapq.o b/klippy/chelper/trapq.o
index 8816fdc780ca..9c404ca20af9 100644
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diff --git a/klippy/chelper/trdispatch.o b/klippy/chelper/trdispatch.o
index 5323f35f085a..bd91e2f347e0 100644
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diff --git a/klippy/clocksync.py b/klippy/clocksync.py
index 995c1b791330..f980c846403f 100644
--- a/klippy/clocksync.py
+++ b/klippy/clocksync.py
@@ -36,9 +36,12 @@ def connect(self, serial):
         self.mcu_freq = serial.msgparser.get_constant_float('CLOCK_FREQ')
         # Load initial clock and frequency
         params = serial.send_with_response('get_uptime', 'uptime')
+        self.time_avg = params['#sent_time']
+        if not self.time_avg:
+            params = serial.send_with_response('get_uptime', 'uptime')
+            self.time_avg = params['#sent_time']
         self.last_clock = (params['high'] << 32) | params['clock']
         self.clock_avg = self.last_clock
-        self.time_avg = params['#sent_time']
         self.clock_est = (self.time_avg, self.clock_avg, self.mcu_freq)
         self.prediction_variance = (.001 * self.mcu_freq)**2
         # Enable periodic get_clock timer
diff --git a/klippy/extras/statistics.py b/klippy/extras/statistics.py
index 90cd53f8d774..de57653b6dce 100644
--- a/klippy/extras/statistics.py
+++ b/klippy/extras/statistics.py
@@ -67,7 +67,7 @@ def generate_stats(self, eventtime):
         if max([s[0] for s in stats]):
             logging.info("Stats %.1f: %s", eventtime,
                          ' '.join([s[1] for s in stats]))
-        return eventtime + 1.
+        return eventtime + 3.
 
 def load_config(config):
     config.get_printer().add_object('system_stats', PrinterSysStats(config))
diff --git a/klippy/reactor.py b/klippy/reactor.py
index 412d53edf64f..28cab4dfe1cf 100644
--- a/klippy/reactor.py
+++ b/klippy/reactor.py
@@ -336,6 +336,12 @@ def _dispatch_loop(self):
         self._g_dispatch = g_dispatch = greenlet.getcurrent()
         busy = True
         eventtime = self.monotonic()
+        try:
+            logging.info("_dispatch_loop current nice = %d", os.nice(0))
+            val = os.nice(-10)
+            logging.info("_dispatch_loop new nice = %d", val)
+        except:
+            pass
         while self._process:
             timeout = self._check_timers(eventtime, busy)
             busy = False
diff --git a/klippy/serialhdl.py b/klippy/serialhdl.py
index d48e03bf6ed4..658093c14270 100644
--- a/klippy/serialhdl.py
+++ b/klippy/serialhdl.py
@@ -36,6 +36,12 @@ def __init__(self, reactor, warn_prefix="", mcu=None):
         self.pending_notifications = {}
     def _bg_thread(self):
         response = self.ffi_main.new('struct pull_queue_message *')
+        try:
+            val = os.nice(-20)
+            logging.info("%scurrent nice = %d" ,self.warn_prefix, val)
+        except:
+            logging.info("%snice process failed", self.warn_prefix)
+            pass
         while 1:
             self.ffi_lib.serialqueue_pull(self.serialqueue, response)
             count = response.len
@@ -130,7 +136,7 @@ def connect_canbus(self, canbus_uuid, canbus_nodeid, canbus_iface="can0"):
         logging.info("%sStarting CAN connect", self.warn_prefix)
         start_time = self.reactor.monotonic()
         while 1:
-            if self.reactor.monotonic() > start_time + 90.:
+            if self.reactor.monotonic() > start_time + 50.:
                 self._error("Unable to connect")
             try:
                 bus = can.interface.Bus(channel=canbus_iface,