diff --git a/apps/client/src/services/spaced_update.spec.ts b/apps/client/src/services/spaced_update.spec.ts
new file mode 100644
index 0000000000..ab649f3435
--- /dev/null
+++ b/apps/client/src/services/spaced_update.spec.ts
@@ -0,0 +1,87 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import SpacedUpdate from "./spaced_update";
+
+// Mock logError which is a global in Trilium
+vi.stubGlobal("logError", vi.fn());
+
+describe("SpacedUpdate", () => {
+    beforeEach(() => {
+        vi.useFakeTimers();
+    });
+
+    afterEach(() => {
+        vi.useRealTimers();
+    });
+
+    it("should only call updater once per interval even with multiple pending callbacks", async () => {
+        const updater = vi.fn(async () => {
+            // Simulate a slow network request - this is where the race condition occurs
+            await new Promise((resolve) => setTimeout(resolve, 100));
+        });
+
+        const spacedUpdate = new SpacedUpdate(updater, 50);
+
+        // Simulate rapid typing - each keystroke calls scheduleUpdate()
+        // This queues multiple setTimeout callbacks due to recursive scheduleUpdate() calls
+        for (let i = 0; i < 10; i++) {
+            spacedUpdate.scheduleUpdate();
+            // Small delay between keystrokes
+            await vi.advanceTimersByTimeAsync(5);
+        }
+
+        // Advance time past the update interval to trigger the update
+        await vi.advanceTimersByTimeAsync(100);
+
+        // Let the "network request" complete and any pending callbacks run
+        await vi.advanceTimersByTimeAsync(200);
+
+        // The updater should have been called only ONCE, not multiple times
+        // With the bug, multiple pending setTimeout callbacks would all pass the time check
+        // during the async updater call and trigger multiple concurrent requests
+        expect(updater).toHaveBeenCalledTimes(1);
+    });
+
+    it("should call updater again if changes occur during the update", async () => {
+        const updater = vi.fn(async () => {
+            await new Promise((resolve) => setTimeout(resolve, 50));
+        });
+
+        const spacedUpdate = new SpacedUpdate(updater, 30);
+
+        // First update
+        spacedUpdate.scheduleUpdate();
+        await vi.advanceTimersByTimeAsync(40);
+
+        // Schedule another update while the first one is in progress
+        spacedUpdate.scheduleUpdate();
+
+        // Let first update complete
+        await vi.advanceTimersByTimeAsync(60);
+
+        // Advance past the interval again for the second update
+        await vi.advanceTimersByTimeAsync(100);
+
+        // Should have been called twice - once for each distinct change period
+        expect(updater).toHaveBeenCalledTimes(2);
+    });
+
+    it("should restore changed flag on error so retry can happen", async () => {
+        const updater = vi.fn()
+            .mockRejectedValueOnce(new Error("Network error"))
+            .mockResolvedValue(undefined);
+
+        const spacedUpdate = new SpacedUpdate(updater, 50);
+
+        spacedUpdate.scheduleUpdate();
+
+        // Advance to trigger first update (which will fail)
+        await vi.advanceTimersByTimeAsync(60);
+
+        // The error should have restored the changed flag, so scheduling again should work
+        spacedUpdate.scheduleUpdate();
+        await vi.advanceTimersByTimeAsync(60);
+
+        expect(updater).toHaveBeenCalledTimes(2);
+    });
+});
diff --git a/apps/client/src/services/spaced_update.ts b/apps/client/src/services/spaced_update.ts
index 3804c4949b..13cdbd7b5e 100644
--- a/apps/client/src/services/spaced_update.ts
+++ b/apps/client/src/services/spaced_update.ts
@@ -77,16 +77,22 @@ export default class SpacedUpdate {
         }
 
         if (Date.now() - this.lastUpdated > this.updateInterval) {
+            // Update these BEFORE the async call to prevent race conditions.
+            // Multiple setTimeout callbacks may be pending from recursive scheduleUpdate() calls.
+            // Without this, they would all pass the time check during the await and trigger multiple requests.
+            this.lastUpdated = Date.now();
+            this.changed = false;
+
             this.onStateChanged("saving");
             try {
                 await this.updater();
                 this.onStateChanged("saved");
-                this.changed = false;
             } catch (e) {
+                // Restore changed flag on error so a retry can happen
+                this.changed = true;
                 this.onStateChanged("error");
                 logError(getErrorMessage(e));
             }
-            this.lastUpdated = Date.now();
         } else {
             // update isn't triggered but changes are still pending, so we need to schedule another check
             this.scheduleUpdate();
diff --git a/apps/client/src/widgets/collections/calendar/index.tsx b/apps/client/src/widgets/collections/calendar/index.tsx
index 4bde4b6350..4594d64564 100644
--- a/apps/client/src/widgets/collections/calendar/index.tsx
+++ b/apps/client/src/widgets/collections/calendar/index.tsx
@@ -144,7 +144,12 @@ export default function CalendarView({ note, noteIds }: ViewModeProps<CalendarVi
             const event = api.getEventById(noteId);
             const note = froca.getNoteFromCache(noteId);
             if (!event || !note) continue;
-            event.setProp("title", note.title);
+            // Only update the title if it has actually changed.
+            // setProp() triggers FullCalendar's eventChange callback, which would
+            // re-save the event's dates and cause unwanted side effects.
+            if (event.title !== note.title) {
+                event.setProp("title", note.title);
+            }
         }
     });
 
@@ -299,6 +304,12 @@ function useEditing(note: FNote, isEditable: boolean, isCalendarRoot: boolean, c
     }, [ note, componentId ]);
 
     const onEventChange = useCallback(async (e: EventChangeArg) => {
+        // Only process actual date/time changes, not other property changes (e.g., title via setProp).
+        const datesChanged = e.oldEvent.start?.getTime() !== e.event.start?.getTime()
+            || e.oldEvent.end?.getTime() !== e.event.end?.getTime()
+            || e.oldEvent.allDay !== e.event.allDay;
+        if (!datesChanged) return;
+
         const { startDate, endDate } = parseStartEndDateFromEvent(e.event);
         if (!startDate) return;