diff --git a/tui_gateway/server.py b/tui_gateway/server.py
index 412c89aaf15..fb98f615fa3 100644
--- a/tui_gateway/server.py
+++ b/tui_gateway/server.py
@@ -8487,11 +8487,19 @@ def _notification_poller_loop(
             _emit("status.update", sid, {"kind": "process", "text": text})
             _emitted.add(_dedup_key)
 
+        _requeued = False
         with session["history_lock"]:
             if session.get("running"):
                 process_registry.completion_queue.put(evt)
-                continue
-            session["running"] = True
+                _requeued = True
+            else:
+                session["running"] = True
+        if _requeued:
+            # Back off before re-polling: the re-queued event keeps the queue
+            # non-empty, so without a sleep this loop spins at full speed
+            # (100% CPU, GIL churn) for as long as the session stays busy.
+            time.sleep(0.25)
+            continue
 
         rid = f"__notif__{int(time.time() * 1000)}"
         try: