diff --git a/frontend/src/components/comments/commentInput.js b/frontend/src/components/comments/commentInput.js
index 839ba179f2..d5ad00ee8b 100644
--- a/frontend/src/components/comments/commentInput.js
+++ b/frontend/src/components/comments/commentInput.js
@@ -48,6 +48,12 @@ export const CommentInputField = ({
     values: async (query, cb) => {
       try {
         if (!query) return cb(contributors.map((username) => ({ username })));
+
+        // address trigger js allowSpaces=true issue
+        // which triggers this function every keystroke
+        const isUsernameAlreadyFetched = /^\[.*?\]\s/.test(query);
+        if (isUsernameAlreadyFetched) return;
+
         const res = await fetchLocalJSONAPI(`users/queries/filter/${query}/`, token);
         cb(res.usernames.map((username) => ({ username })));
       } catch (e) {