diff --git a/src/components/AiChat.vue b/src/components/AiChat.vue
index e9f9bd9..b36e121 100644
--- a/src/components/AiChat.vue
+++ b/src/components/AiChat.vue
@@ -197,7 +197,7 @@
                 class="ai-msg-bubble ai-msg-bubble--ai ai-md"
                 :class="{ 'ai-msg-bubble--error': msg.isError }"
               >
-                <div v-html="renderMd(isLastAi(msg) && store.state.currentText ? store.state.currentText : msg.content)"></div>
+                <div v-html="renderMd(isLastAi(msg) && store.state.currentText ? store.state.currentText : msg.content, isLastAi(msg) && store.state.streaming)"></div>
                 <span v-if="isLastAi(msg) && isViewingGenerating" class="ai-cursor"></span>
               </div>
               <!-- 流式开始但尚无文本时显示光标 -->
@@ -344,14 +344,16 @@ function escapeHtml(text: string): string {
   return text.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;')
 }
 
-function renderMd(text: string): string {
+function renderMd(text: string, isStreaming = false): string {
   if (!text) return ''
+  // 流式态纯文本(AR-1):避免每 delta 全量 marked.parse+sanitize 致主线程阻塞掉帧;
+  // 不缓存流式文本(每 delta 变,缓存无收益且污染),仅 escapeHtml + 换行转 <br>;完成后再走 markdown
+  if (isStreaming || !mdReady.value || !_marked || !_purify) {
+    return escapeHtml(text).replace(/\n/g, '<br>')
+  }
   const cached = _mdCache.get(text)
   if (cached !== undefined) return cached
-  // 依赖 mdReady 使加载完成后自动重渲染；未就绪时先以纯文本兜底
-  const html = (!mdReady.value || !_marked || !_purify)
-    ? escapeHtml(text)
-    : _purify.sanitize(_marked.parse(text) as string)
+  const html = _purify.sanitize(_marked.parse(text) as string)
   if (_mdCache.size > 200) _mdCache.clear()
   _mdCache.set(text, html)
   return html