.patch

diff --git a/lib/components/chat-mention-provider.react.js b/lib/components/chat-mention-provider.react.js
index 2daededbd..8059de95a 100644
--- a/lib/components/chat-mention-provider.react.js
+++ b/lib/components/chat-mention-provider.react.js
@@ -77,6 +77,7 @@ function getChatMentionCandidates(threadInfos: {
   chatMentionCandidatesObj: ChatMentionCandidatesObj,
   communityThreadIDForGenesisThreads: { +[id: string]: string },
 } {
+  const start = Date.now();
   const result = {};
   const visitedGenesisThreads = new Set();
   const communityThreadIDForGenesisThreads = {};
@@ -170,6 +171,7 @@ function getChatMentionCandidates(threadInfos: {
     }
     result[currentThreadCommunity][currentThreadID] = currentThreadInfo;
   }
+  console.log(`getChatMentionCandidates took ${Date.now() - start}ms`);
   return {
     chatMentionCandidatesObj: result,
     communityThreadIDForGenesisThreads,
@@ -210,25 +212,39 @@ function useChatMentionSearchIndex(
   +[id: string]: SentencePrefixSearchIndex,
 } {
   return React.useMemo(() => {
+    const start = Date.now();
     const result = {};
     for (const communityThreadID in chatMentionCandidatesObj) {
       const searchIndex = new SentencePrefixSearchIndex();
       const searchIndexEntries = [];
+      const start2 = Date.now();
       for (const threadID in chatMentionCandidatesObj[communityThreadID]) {
         searchIndexEntries.push({
           id: threadID,
           uiName: chatMentionCandidatesObj[communityThreadID][threadID].uiName,
         });
       }
+      if (Date.now() - start2 >= 2) {
+        console.log(`community ${communityThreadID} took ${Date.now() - start2}ms to collect searchIndexEntries`);
+      }
       // Sort the keys so that the order of the search result is consistent
+      const start3 = Date.now();
       searchIndexEntries.sort(({ uiName: uiNameA }, { uiName: uiNameB }) =>
         uiNameA.localeCompare(uiNameB),
       );
+      if (Date.now() - start3 >= 2) {
+        console.log(`community ${communityThreadID} took ${Date.now() - start3}ms to sort searchIndexEntries`);
+      }
+      const start4 = Date.now();
       for (const { id, uiName } of searchIndexEntries) {
         searchIndex.addEntry(id, uiName);
       }
+      if (Date.now() - start4 >= 2) {
+        console.log(`community ${communityThreadID} took ${Date.now() - start4}ms to add ${searchIndexEntries.length} entries into a RadixTree. ${searchIndex.getAndResetCounter()}ms was for tokenization`);
+      }
       result[communityThreadID] = searchIndex;
     }
+    console.log(`useChatMentionSearchIndex took ${Date.now() - start}ms. total of ${Object.keys(result).length} SearchIndexes`);
     return result;
   }, [chatMentionCandidatesObj]);
 }
diff --git a/lib/shared/sentence-prefix-search-index.js b/lib/shared/sentence-prefix-search-index.js
index bc85bd7cf..ed6f75d6e 100644
--- a/lib/shared/sentence-prefix-search-index.js
+++ b/lib/shared/sentence-prefix-search-index.js
@@ -10,6 +10,7 @@ const tokenize = new Tokenizer().re(/\S+/);
 
 class SentencePrefixSearchIndex extends SearchIndex {
   entries: Set<string>;
+  counter: number = 0;
 
   constructor() {
     super(tokenize);
@@ -17,7 +18,13 @@ class SentencePrefixSearchIndex extends SearchIndex {
   }
 
   addEntry(id: string, rawText: string) {
+    const start = Date.now();
     const keywords = this.tokenize(rawText);
+    //console.log(`${rawText} -> ${JSON.stringify(keywords)}`);
+    this.counter += Date.now() - start;
+    if (start - Date.now() >= 2) {
+      console.log(`tokenize() took ${Date.now() - start} for ${id} (${rawText})`);
+    }
     for (const keyword of keywords) {
       const value = rawText.slice(keyword.index).toLowerCase();
       this.addAllPrefixes(id, value);
@@ -28,6 +35,12 @@ class SentencePrefixSearchIndex extends SearchIndex {
   getSearchResults(query: string): string[] {
     return this.radixTree.getAllMatchingPrefix(query.toLowerCase());
   }
+
+  getAndResetCounter(): number {
+    const { counter } = this;
+    this.counter = 0;
+    return counter;
+  }
 }
 
 export default SentencePrefixSearchIndex;