diff --git a/ui/src/components/MarkdownEditor.tsx b/ui/src/components/MarkdownEditor.tsx
index 223b5755631..d9edaf6c175 100644
--- a/ui/src/components/MarkdownEditor.tsx
+++ b/ui/src/components/MarkdownEditor.tsx
@@ -509,11 +509,21 @@ export const MarkdownEditor = forwardRef<MarkdownEditorRef, MarkdownEditorProps>
     // also fires after typing (e.g. space to dismiss).
     const onInput = () => requestAnimationFrame(checkMention);
 
-    document.addEventListener("selectionchange", checkMention);
+    let selRafId: number | null = null;
+    const onSelectionChange = () => {
+      if (selRafId !== null) return;
+      selRafId = requestAnimationFrame(() => {
+        selRafId = null;
+        checkMention();
+      });
+    };
+
+    document.addEventListener("selectionchange", onSelectionChange);
     el?.addEventListener("input", onInput, true);
     return () => {
-      document.removeEventListener("selectionchange", checkMention);
+      document.removeEventListener("selectionchange", onSelectionChange);
       el?.removeEventListener("input", onInput, true);
+      if (selRafId !== null) cancelAnimationFrame(selRafId);
     };
   }, [checkMention, mentions, slashCommands.length]);
 
@@ -540,15 +550,23 @@ export const MarkdownEditor = forwardRef<MarkdownEditorRef, MarkdownEditorProps>
     const editable = containerRef.current?.querySelector('[contenteditable="true"]');
     if (!editable) return;
     decorateProjectMentions();
+    let rafId: number | null = null;
     const observer = new MutationObserver(() => {
-      decorateProjectMentions();
+      if (rafId !== null) return;
+      rafId = requestAnimationFrame(() => {
+        rafId = null;
+        decorateProjectMentions();
+      });
     });
     observer.observe(editable, {
       subtree: true,
       childList: true,
       characterData: true,
     });
-    return () => observer.disconnect();
+    return () => {
+      observer.disconnect();
+      if (rafId !== null) cancelAnimationFrame(rafId);
+    };
   }, [decorateProjectMentions]);
 
   const selectMention = useCallback(