diff --git a/frontend/components/chat/MessageContent.vue b/frontend/components/chat/MessageContent.vue
index 80dc364..d50cbf4 100644
--- a/frontend/components/chat/MessageContent.vue
+++ b/frontend/components/chat/MessageContent.vue
@@ -30,8 +30,17 @@
                   </div>
                   <div v-else-if="message.renderType === 'image'"
                     class="max-w-sm">
-                    <div class="msg-radius overflow-hidden cursor-pointer" :class="message.isSent ? '' : ''" @click="message.imageUrl && openImagePreview(message.imageUrl)" @contextmenu="openMediaContextMenu($event, message, 'image')">
-                      <img v-if="message.imageUrl" :src="message.imageUrl" alt="图片" class="max-w-[240px] max-h-[240px] object-cover hover:opacity-90 transition-opacity">
+                  <div class="msg-radius overflow-hidden cursor-pointer" :class="message.isSent ? '' : ''" @click="message.imageUrl && openImagePreview(message.imageUrl)" @contextmenu="openMediaContextMenu($event, message, 'image')">
+                      <img
+                        v-if="message.imageUrl"
+                        v-chat-lazy-src="message.imageUrl"
+                        alt="图片"
+                        class="block min-w-[96px] min-h-[96px] max-w-[240px] max-h-[240px] object-cover bg-gray-100 hover:opacity-90 transition-opacity"
+                        loading="lazy"
+                        decoding="async"
+                        fetchpriority="low"
+                        v-chat-media-perf="{ kind: 'message-image', meta: { conversation: selectedContact?.username || '', messageId: message.id, serverId: message.serverIdStr || '', imageMd5: message.imageMd5 || '', imageFileId: message.imageFileId || '' } }"
+                      >
                       <div v-else class="px-3 py-2 text-sm max-w-sm relative msg-bubble whitespace-pre-wrap break-words leading-relaxed"
                         :class="message.isSent ? 'bg-[#95EC69] text-black bubble-tail-r' : 'bg-white text-gray-800 bubble-tail-l'">
                         {{ message.content }}
@@ -40,7 +49,16 @@
                   </div>
                   <div v-else-if="message.renderType === 'video'" class="max-w-sm">
                     <div class="msg-radius overflow-hidden relative bg-black/5" @contextmenu="openMediaContextMenu($event, message, 'video')">
-                      <img v-if="message.videoThumbUrl" :src="message.videoThumbUrl" alt="视频" class="block w-[220px] max-w-[260px] h-auto max-h-[260px] object-cover">
+                      <img
+                        v-if="message.videoThumbUrl"
+                        v-chat-lazy-src="message.videoThumbUrl"
+                        alt="视频"
+                        class="block w-[220px] min-h-[120px] max-w-[260px] h-auto max-h-[260px] object-cover bg-gray-100"
+                        loading="lazy"
+                        decoding="async"
+                        fetchpriority="low"
+                        v-chat-media-perf="{ kind: 'message-video-thumb', meta: { conversation: selectedContact?.username || '', messageId: message.id, serverId: message.serverIdStr || '', videoThumbMd5: message.videoThumbMd5 || '', videoThumbFileId: message.videoThumbFileId || '' } }"
+                      >
                       <div v-else class="px-3 py-2 text-sm relative msg-bubble whitespace-pre-wrap break-words leading-relaxed"
                         :class="message.isSent ? 'bg-[#95EC69] text-black bubble-tail-r' : 'bg-white text-gray-800 bubble-tail-l'">
                         {{ message.content }}
@@ -100,7 +118,15 @@
                   </div>
                   <div v-else-if="message.renderType === 'emoji'" class="max-w-sm flex items-center group" :class="message.isSent ? 'flex-row-reverse' : ''">
                     <template v-if="message.emojiUrl">
-                      <img :src="message.emojiUrl" alt="表情" class="w-24 h-24 object-contain" @contextmenu="openMediaContextMenu($event, message, 'emoji')">
+                      <img
+                        v-chat-lazy-src="message.emojiUrl"
+                        alt="表情"
+                        class="w-24 h-24 object-contain"
+                        loading="lazy"
+                        decoding="async"
+                        fetchpriority="low"
+                        @contextmenu="openMediaContextMenu($event, message, 'emoji')"
+                      >
                       <button
                         v-if="shouldShowEmojiDownload(message)"
                         class="text-xs px-2 py-1 rounded bg-white border border-gray-200 text-gray-700 opacity-0 group-hover:opacity-100 transition-opacity"
@@ -122,7 +148,7 @@
                       :class="message.isSent ? 'bg-[#95EC69] text-black bubble-tail-r' : 'bg-white text-gray-800 bubble-tail-l'">
                       <span v-for="(seg, idx) in parseTextWithEmoji(message.content)" :key="idx">
                         <span v-if="seg.type === 'text'">{{ seg.content }}</span>
-                        <img v-else :src="seg.emojiSrc" :alt="seg.content" class="inline-block w-[1.25em] h-[1.25em] align-text-bottom mx-px">
+                        <img v-else :src="seg.emojiSrc" :alt="seg.content" class="inline-block w-[1.25em] h-[1.25em] align-text-bottom mx-px" loading="lazy" decoding="async">
                       </span>
                     </div>
                       <div
@@ -189,13 +215,15 @@
                          class="ml-2 my-2 flex-shrink-0 max-w-[98px] max-h-[49px] overflow-hidden flex items-center justify-center cursor-pointer"
                          @click.stop="openImagePreview(message.quoteThumbUrl)"
                        >
-                         <img
-                           :src="message.quoteThumbUrl"
-                           alt="引用链接缩略图"
-                           class="max-h-[49px] w-auto max-w-[98px] object-contain"
-                           loading="lazy"
-                           decoding="async"
-                           referrerpolicy="no-referrer"
+                          <img
+                            v-chat-lazy-src="message.quoteThumbUrl"
+                            alt="引用链接缩略图"
+                            class="max-h-[49px] w-auto max-w-[98px] object-contain"
+                            loading="lazy"
+                            decoding="async"
+                            fetchpriority="low"
+                            referrerpolicy="no-referrer"
+                            v-chat-media-perf="{ kind: 'quote-thumb', meta: { conversation: selectedContact?.username || '', messageId: message.id, quoteServerId: message.quoteServerId || '' } }"
                            @error="onQuoteThumbError(message)"
                          />
                        </div>
@@ -204,12 +232,14 @@
                          class="ml-2 my-2 flex-shrink-0 max-w-[98px] max-h-[49px] overflow-hidden flex items-center justify-center cursor-pointer"
                          @click.stop="openImagePreview(message.quoteImageUrl)"
                        >
-                         <img
-                           :src="message.quoteImageUrl"
-                           alt="引用图片"
-                           class="max-h-[49px] w-auto max-w-[98px] object-contain"
-                           loading="lazy"
-                           decoding="async"
+                          <img
+                            v-chat-lazy-src="message.quoteImageUrl"
+                            alt="引用图片"
+                            class="max-h-[49px] w-auto max-w-[98px] object-contain"
+                            loading="lazy"
+                            decoding="async"
+                            fetchpriority="low"
+                            v-chat-media-perf="{ kind: 'quote-image', meta: { conversation: selectedContact?.username || '', messageId: message.id, quoteServerId: message.quoteServerId || '' } }"
                            @error="onQuoteImageError(message)"
                          />
                        </div>
diff --git a/frontend/components/chat/MessageItem.vue b/frontend/components/chat/MessageItem.vue
index cab78d9..2a457ab 100644
--- a/frontend/components/chat/MessageItem.vue
+++ b/frontend/components/chat/MessageItem.vue
@@ -31,10 +31,14 @@
           <div class="w-[calc(42px/var(--dpr))] h-[calc(42px/var(--dpr))] rounded-md overflow-hidden bg-gray-300 flex-shrink-0" :class="[message.isSent ? 'ml-3' : 'mr-3', { 'privacy-blur': privacyMode }]">
             <div v-if="message.avatar" class="w-full h-full">
               <img
-                :src="message.avatar"
+                v-chat-lazy-src="message.avatar"
                 :alt="message.sender + '的头像'"
                 class="w-full h-full object-cover"
+                loading="lazy"
+                decoding="async"
+                fetchpriority="low"
                 referrerpolicy="no-referrer"
+                v-chat-media-perf="{ kind: 'message-avatar', meta: { conversation: selectedContact?.username || '', messageId: message.id, serverId: message.serverIdStr || '', senderUsername: message.senderUsername || '' } }"
                 @error="onAvatarError($event, message)"
               >
             </div>
diff --git a/frontend/lib/chat/perf-logger.js b/frontend/lib/chat/perf-logger.js
new file mode 100644
index 0000000..2b8984b
--- /dev/null
+++ b/frontend/lib/chat/perf-logger.js
@@ -0,0 +1,76 @@
+const roundPerfMs = (value) => {
+  const numeric = Number(value)
+  if (!Number.isFinite(numeric)) return null
+  return Number(numeric.toFixed(1))
+}
+
+const isDesktopShell = () => {
+  if (typeof window === 'undefined') return false
+  return !!window.wechatDesktop?.__brand
+}
+
+export const nowPerfMs = () => {
+  if (typeof performance !== 'undefined' && typeof performance.now === 'function') {
+    return performance.now()
+  }
+  return Date.now()
+}
+
+export const logPerfChannel = (channel, phase, details = {}) => {
+  const payload = { ...details }
+  if (isDesktopShell()) {
+    try {
+      window.wechatDesktop?.logDebug?.(channel, phase, payload)
+    } catch {}
+  }
+  try {
+    console.info(`[${channel}] ${phase}`, payload)
+  } catch {}
+}
+
+export const createPerfTrace = (channel, baseDetails = {}) => {
+  const traceId = `${channel}-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`
+  const startedAt = nowPerfMs()
+  let lastAt = startedAt
+
+  return {
+    id: traceId,
+    log(phase, details = {}) {
+      const now = nowPerfMs()
+      const payload = {
+        ...baseDetails,
+        ...details,
+        traceId,
+        elapsedMs: roundPerfMs(now - startedAt),
+        deltaMs: roundPerfMs(now - lastAt)
+      }
+      lastAt = now
+      logPerfChannel(channel, phase, payload)
+      return payload
+    }
+  }
+}
+
+export const getLatestResourceTiming = (resourceUrl) => {
+  const url = String(resourceUrl || '').trim()
+  if (!url || typeof performance === 'undefined' || typeof performance.getEntriesByName !== 'function') {
+    return {}
+  }
+
+  try {
+    const entries = performance.getEntriesByName(url)
+    if (!entries?.length) return {}
+    const entry = entries[entries.length - 1]
+    return {
+      resourceDurationMs: roundPerfMs(entry.duration),
+      fetchStartMs: roundPerfMs(entry.fetchStart),
+      responseEndMs: roundPerfMs(entry.responseEnd),
+      transferSize: Number.isFinite(entry.transferSize) ? Number(entry.transferSize) : null,
+      encodedBodySize: Number.isFinite(entry.encodedBodySize) ? Number(entry.encodedBodySize) : null,
+      decodedBodySize: Number.isFinite(entry.decodedBodySize) ? Number(entry.decodedBodySize) : null,
+      initiatorType: String(entry.initiatorType || '').trim()
+    }
+  } catch {
+    return {}
+  }
+}
diff --git a/frontend/plugins/chat-media-perf.client.js b/frontend/plugins/chat-media-perf.client.js
new file mode 100644
index 0000000..5cbcb05
--- /dev/null
+++ b/frontend/plugins/chat-media-perf.client.js
@@ -0,0 +1,232 @@
+import { createPerfTrace, getLatestResourceTiming } from '~/lib/chat/perf-logger'
+
+const CHAT_LAZY_SRC_EVENT = 'chat-lazy-src:start'
+const CHAT_LAZY_ROOT_MARGIN = '240px 0px 520px 0px'
+
+const nextRenderTick = (callback) => {
+  if (typeof window === 'undefined') {
+    setTimeout(callback, 0)
+    return
+  }
+  if (typeof window.requestAnimationFrame !== 'function') {
+    window.setTimeout(callback, 0)
+    return
+  }
+  window.requestAnimationFrame(() => {
+    window.setTimeout(callback, 0)
+  })
+}
+
+const readImageSrc = (element) => {
+  return String(
+    element?.currentSrc
+    || element?.getAttribute?.('src')
+    || element?.src
+    || ''
+  ).trim()
+}
+
+const normalizeBindingValue = (value) => {
+  if (!value || typeof value !== 'object') {
+    return { kind: 'image', meta: {} }
+  }
+  return {
+    kind: String(value.kind || 'image').trim() || 'image',
+    meta: value.meta && typeof value.meta === 'object' ? { ...value.meta } : {}
+  }
+}
+
+const ensurePerfState = (element) => {
+  if (!element.__chatMediaPerfState) {
+    element.__chatMediaPerfState = {
+      src: '',
+      trace: null,
+      finalized: true,
+      onLoad: null,
+      onError: null,
+      onLazyStart: null
+    }
+  }
+  return element.__chatMediaPerfState
+}
+
+const normalizeLazySrc = (value) => {
+  if (value == null) return ''
+  if (typeof value === 'string') return value.trim()
+  if (typeof value === 'object') return String(value.src || '').trim()
+  return String(value || '').trim()
+}
+
+const ensureLazySrcState = (element) => {
+  if (!element.__chatLazySrcState) {
+    element.__chatLazySrcState = {
+      src: '',
+      loadedSrc: '',
+      observer: null,
+      timer: null
+    }
+  }
+  return element.__chatLazySrcState
+}
+
+const cleanupLazySrcObserver = (element) => {
+  const state = element?.__chatLazySrcState
+  if (!state) return
+  if (state.observer) {
+    try { state.observer.disconnect() } catch {}
+    state.observer = null
+  }
+  if (state.timer) {
+    try { clearTimeout(state.timer) } catch {}
+    state.timer = null
+  }
+}
+
+const applyLazySrc = (element, reason = '') => {
+  const state = element?.__chatLazySrcState
+  const src = String(state?.src || '').trim()
+  if (!element || !src) return
+  if (state.loadedSrc === src && readImageSrc(element) === src) return
+
+  state.loadedSrc = src
+  element.setAttribute('src', src)
+  try {
+    element.dispatchEvent(new CustomEvent(CHAT_LAZY_SRC_EVENT, {
+      detail: { src, reason }
+    }))
+  } catch {}
+}
+
+const updateLazySrc = (element, binding, reason = '') => {
+  const state = ensureLazySrcState(element)
+  const nextSrc = normalizeLazySrc(binding?.value)
+
+  cleanupLazySrcObserver(element)
+  state.src = nextSrc
+
+  if (!nextSrc) {
+    state.loadedSrc = ''
+    try { element.removeAttribute('src') } catch {}
+    return
+  }
+
+  if (state.loadedSrc !== nextSrc || readImageSrc(element) !== nextSrc) {
+    state.loadedSrc = ''
+    try { element.removeAttribute('src') } catch {}
+    try { element.setAttribute('data-chat-lazy-src', nextSrc) } catch {}
+  }
+
+  if (typeof window === 'undefined' || typeof window.IntersectionObserver !== 'function') {
+    state.timer = setTimeout(() => applyLazySrc(element, `${reason}:fallback`), 0)
+    return
+  }
+
+  state.observer = new window.IntersectionObserver((entries) => {
+    const entry = entries?.[0]
+    if (!entry?.isIntersecting) return
+    cleanupLazySrcObserver(element)
+    applyLazySrc(element, `${reason}:intersect`)
+  }, {
+    root: null,
+    rootMargin: CHAT_LAZY_ROOT_MARGIN,
+    threshold: 0.01
+  })
+  state.observer.observe(element)
+}
+
+const finalizeTracking = (element, status, reason = '') => {
+  const state = element?.__chatMediaPerfState
+  if (!state?.trace || state.finalized) return
+
+  const currentSrc = readImageSrc(element) || state.src
+  state.trace.log(status === 'load' ? 'resource:load' : 'resource:error', {
+    reason,
+    currentSrc,
+    complete: !!element?.complete,
+    naturalWidth: Number(element?.naturalWidth || 0),
+    naturalHeight: Number(element?.naturalHeight || 0),
+    ...getLatestResourceTiming(currentSrc)
+  })
+  state.finalized = true
+}
+
+const beginTracking = (element, binding, reason = '') => {
+  const state = ensurePerfState(element)
+  const src = readImageSrc(element)
+  if (!src) return
+  if (state.src === src && state.trace && !state.finalized) return
+
+  const { kind, meta } = normalizeBindingValue(binding?.value)
+  state.src = src
+  state.finalized = false
+  state.trace = createPerfTrace('chat-media-ui', {
+    kind,
+    src,
+    ...meta
+  })
+  state.trace.log('resource:start', {
+    reason,
+    complete: !!element?.complete,
+    loading: String(element?.getAttribute?.('loading') || '').trim(),
+    decoding: String(element?.getAttribute?.('decoding') || '').trim()
+  })
+
+  if (element?.complete) {
+    nextRenderTick(() => finalizeTracking(element, 'load', 'complete-sync'))
+  }
+}
+
+export default defineNuxtPlugin((nuxtApp) => {
+  nuxtApp.vueApp.directive('chat-media-perf', {
+    mounted(element, binding) {
+      const state = ensurePerfState(element)
+      state.onLoad = () => finalizeTracking(element, 'load', 'load-event')
+      state.onError = () => finalizeTracking(element, 'error', 'error-event')
+      state.onLazyStart = () => beginTracking(element, binding, 'lazy-src')
+      element.addEventListener('load', state.onLoad)
+      element.addEventListener('error', state.onError)
+      element.addEventListener(CHAT_LAZY_SRC_EVENT, state.onLazyStart)
+      beginTracking(element, binding, 'mounted')
+    },
+    updated(element, binding) {
+      const state = ensurePerfState(element)
+      const nextSrc = readImageSrc(element)
+      if (!nextSrc) return
+      if (nextSrc !== state.src) {
+        beginTracking(element, binding, 'updated-src')
+        return
+      }
+      if (element?.complete && !state.finalized) {
+        nextRenderTick(() => finalizeTracking(element, 'load', 'updated-complete'))
+      }
+    },
+    beforeUnmount(element) {
+      const state = element?.__chatMediaPerfState
+      if (state?.onLoad) element.removeEventListener('load', state.onLoad)
+      if (state?.onError) element.removeEventListener('error', state.onError)
+      if (state?.onLazyStart) element.removeEventListener(CHAT_LAZY_SRC_EVENT, state.onLazyStart)
+      if (state?.trace && !state.finalized) {
+        finalizeTracking(element, element?.complete ? 'load' : 'error', 'before-unmount')
+      }
+      delete element.__chatMediaPerfState
+    }
+  })
+
+  nuxtApp.vueApp.directive('chat-lazy-src', {
+    mounted(element, binding) {
+      updateLazySrc(element, binding, 'mounted')
+    },
+    updated(element, binding) {
+      const state = ensureLazySrcState(element)
+      const nextSrc = normalizeLazySrc(binding?.value)
+      if (nextSrc === state.src && (state.loadedSrc === nextSrc || !readImageSrc(element))) {
+        return
+      }
+      updateLazySrc(element, binding, 'updated')
+    },
+    beforeUnmount(element) {
+      cleanupLazySrcObserver(element)
+      delete element.__chatLazySrcState
+    }
+  })
+})