diff --git a/ui/src/components/CommentThread.tsx b/ui/src/components/CommentThread.tsx
index 3ebcb0bf..b1c2271a 100644
--- a/ui/src/components/CommentThread.tsx
+++ b/ui/src/components/CommentThread.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useMemo, useRef, useState, type ChangeEvent } from "react";
+import { memo, useEffect, useMemo, useRef, useState, type ChangeEvent } from "react";
 import { Link } from "react-router-dom";
 import type { IssueComment, Agent } from "@paperclipai/shared";
 import { Button } from "@/components/ui/button";
@@ -95,6 +95,91 @@ type TimelineItem =
   | { kind: "comment"; id: string; createdAtMs: number; comment: CommentWithRunMeta }
   | { kind: "run"; id: string; createdAtMs: number; run: LinkedRunItem };
 
+const TimelineList = memo(function TimelineList({
+  timeline,
+  agentMap,
+}: {
+  timeline: TimelineItem[];
+  agentMap?: Map<string, Agent>;
+}) {
+  if (timeline.length === 0) {
+    return <p className="text-sm text-muted-foreground">No comments or runs yet.</p>;
+  }
+
+  return (
+    <div className="space-y-3">
+      {timeline.map((item) => {
+        if (item.kind === "run") {
+          const run = item.run;
+          return (
+            <div key={`run:${run.runId}`} className="border border-border bg-accent/20 p-3 overflow-hidden min-w-0 rounded-sm">
+              <div className="flex items-center justify-between mb-2">
+                <Link to={`/agents/${run.agentId}`} className="hover:underline">
+                  <Identity
+                    name={agentMap?.get(run.agentId)?.name ?? run.agentId.slice(0, 8)}
+                    size="sm"
+                  />
+                </Link>
+                <span className="text-xs text-muted-foreground">
+                  {formatDateTime(run.startedAt ?? run.createdAt)}
+                </span>
+              </div>
+              <div className="flex items-center gap-2 text-xs">
+                <span className="text-muted-foreground">Run</span>
+                <Link
+                  to={`/agents/${run.agentId}/runs/${run.runId}`}
+                  className="inline-flex items-center rounded-md border border-border bg-accent/40 px-2 py-1 font-mono text-muted-foreground hover:text-foreground hover:bg-accent/60 transition-colors"
+                >
+                  {run.runId.slice(0, 8)}
+                </Link>
+                <StatusBadge status={run.status} />
+              </div>
+            </div>
+          );
+        }
+
+        const comment = item.comment;
+        return (
+          <div key={comment.id} className="border border-border p-3 overflow-hidden min-w-0 rounded-sm">
+            <div className="flex items-center justify-between mb-1">
+              {comment.authorAgentId ? (
+                <Link to={`/agents/${comment.authorAgentId}`} className="hover:underline">
+                  <Identity
+                    name={agentMap?.get(comment.authorAgentId)?.name ?? comment.authorAgentId.slice(0, 8)}
+                    size="sm"
+                  />
+                </Link>
+              ) : (
+                <Identity name="You" size="sm" />
+              )}
+              <span className="text-xs text-muted-foreground">
+                {formatDateTime(comment.createdAt)}
+              </span>
+            </div>
+            <MarkdownBody className="text-sm">{comment.body}</MarkdownBody>
+            {comment.runId && (
+              <div className="mt-2 pt-2 border-t border-border/60">
+                {comment.runAgentId ? (
+                  <Link
+                    to={`/agents/${comment.runAgentId}/runs/${comment.runId}`}
+                    className="inline-flex items-center rounded-md border border-border bg-accent/30 px-2 py-1 text-[10px] font-mono text-muted-foreground hover:text-foreground hover:bg-accent/50 transition-colors"
+                  >
+                    run {comment.runId.slice(0, 8)}
+                  </Link>
+                ) : (
+                  <span className="inline-flex items-center rounded-md border border-border bg-accent/30 px-2 py-1 text-[10px] font-mono text-muted-foreground">
+                    run {comment.runId.slice(0, 8)}
+                  </span>
+                )}
+              </div>
+            )}
+          </div>
+        );
+      })}
+    </div>
+  );
+});
+
 export function CommentThread({
   comments,
   linkedRuns = [],
@@ -212,80 +297,7 @@ export function CommentThread({
     <div className="space-y-4">
       <h3 className="text-sm font-semibold">Comments &amp; Runs ({timeline.length})</h3>
 
-      {timeline.length === 0 && (
-        <p className="text-sm text-muted-foreground">No comments or runs yet.</p>
-      )}
-
-      <div className="space-y-3">
-        {timeline.map((item) => {
-          if (item.kind === "run") {
-            const run = item.run;
-            return (
-              <div key={`run:${run.runId}`} className="border border-border bg-accent/20 p-3 overflow-hidden min-w-0 rounded-sm">
-                <div className="flex items-center justify-between mb-2">
-                  <Link to={`/agents/${run.agentId}`} className="hover:underline">
-                    <Identity
-                      name={agentMap?.get(run.agentId)?.name ?? run.agentId.slice(0, 8)}
-                      size="sm"
-                    />
-                  </Link>
-                  <span className="text-xs text-muted-foreground">
-                    {formatDateTime(run.startedAt ?? run.createdAt)}
-                  </span>
-                </div>
-                <div className="flex items-center gap-2 text-xs">
-                  <span className="text-muted-foreground">Run</span>
-                  <Link
-                    to={`/agents/${run.agentId}/runs/${run.runId}`}
-                    className="inline-flex items-center rounded-md border border-border bg-accent/40 px-2 py-1 font-mono text-muted-foreground hover:text-foreground hover:bg-accent/60 transition-colors"
-                  >
-                    {run.runId.slice(0, 8)}
-                  </Link>
-                  <StatusBadge status={run.status} />
-                </div>
-              </div>
-            );
-          }
-
-          const comment = item.comment;
-          return (
-            <div key={comment.id} className="border border-border p-3 overflow-hidden min-w-0 rounded-sm">
-              <div className="flex items-center justify-between mb-1">
-                {comment.authorAgentId ? (
-                  <Link to={`/agents/${comment.authorAgentId}`} className="hover:underline">
-                    <Identity
-                      name={agentMap?.get(comment.authorAgentId)?.name ?? comment.authorAgentId.slice(0, 8)}
-                      size="sm"
-                    />
-                  </Link>
-                ) : (
-                  <Identity name="You" size="sm" />
-                )}
-                <span className="text-xs text-muted-foreground">
-                  {formatDateTime(comment.createdAt)}
-                </span>
-              </div>
-              <MarkdownBody className="text-sm">{comment.body}</MarkdownBody>
-              {comment.runId && (
-                <div className="mt-2 pt-2 border-t border-border/60">
-                  {comment.runAgentId ? (
-                    <Link
-                      to={`/agents/${comment.runAgentId}/runs/${comment.runId}`}
-                      className="inline-flex items-center rounded-md border border-border bg-accent/30 px-2 py-1 text-[10px] font-mono text-muted-foreground hover:text-foreground hover:bg-accent/50 transition-colors"
-                    >
-                      run {comment.runId.slice(0, 8)}
-                    </Link>
-                  ) : (
-                    <span className="inline-flex items-center rounded-md border border-border bg-accent/30 px-2 py-1 text-[10px] font-mono text-muted-foreground">
-                      run {comment.runId.slice(0, 8)}
-                    </span>
-                  )}
-                </div>
-              )}
-            </div>
-          );
-        })}
-      </div>
+      <TimelineList timeline={timeline} agentMap={agentMap} />
 
       {liveRunSlot}