diff --git a/changelog/3881.added.md b/changelog/3881.added.md
new file mode 100644
index 000000000..694e052ce
--- /dev/null
+++ b/changelog/3881.added.md
@@ -0,0 +1 @@
+- Added `StartupTimingObserver` for measuring how long each processor's `start()` method takes during pipeline startup. Useful for diagnosing cold start slowness and identifying initialization bottlenecks.