diff --git a/apps/stage-web/README.md b/apps/stage-web/README.md
index 3233e4cf2..819911820 100644
--- a/apps/stage-web/README.md
+++ b/apps/stage-web/README.md
@@ -5,3 +5,20 @@
 </p>
 
 > Heavily inspired by [Neuro-sama](https://www.youtube.com/@Neurosama)
+
+## Performance diagnostics
+
+Run `pnpm dev:web:https` from the repository root. Open `/devtools/performance-visualizer` and enable FPS.
+The floating overlay shows the last 10 seconds of FPS history, with time and FPS axes.
+The minimum, maximum, and latest values describe the visible samples. Other metrics retain their distribution charts.
+
+Start a recording, then navigate within the app to the scene you want to measure.
+Stop the recording within 60 seconds, or let it stop automatically.
+Return to the visualizer to inspect the recorded FPS history. Export the recording as CSV for individual timestamps and values.
+
+Each FPS sample is `1000 / frameIntervalMs`, from `requestAnimationFrame` callbacks.
+Use these samples to locate changes in animation frame timing. They do not measure GPU presentation or native application FPS.
+Keep the page in the foreground. Reloading the page clears the recording.
+
+For device comparisons, use the same scene, model, warm-up period, and recording duration.
+The development server and the visible overlay affect performance, so record these conditions with the results.
diff --git a/apps/stage-web/src/components/Devtools/PerformanceOverlay.vue b/apps/stage-web/src/components/Devtools/PerformanceOverlay.vue
index 0f2518f62..da57d80ab 100644
--- a/apps/stage-web/src/components/Devtools/PerformanceOverlay.vue
+++ b/apps/stage-web/src/components/Devtools/PerformanceOverlay.vue
@@ -8,6 +8,8 @@ import { storeToRefs } from 'pinia'
 import { computed, shallowRef, useTemplateRef, watch } from 'vue'
 import { useI18n } from 'vue-i18n'
 
+import FpsHistory from './fps-history.vue'
+
 import { useDevtoolsLagStore } from '../../stores/devtools-lag'
 
 const { n, t } = useI18n()
@@ -56,6 +58,7 @@ const metricsWithStats = computed(() => visibleMetrics.value.map(metric => ({
   stats: metricStatsMap.value[metric.key],
 })))
 const recordingElapsedSeconds = computed(() => Math.min(60, Math.floor(recordingElapsedMs.value / 1000)))
+const fpsHistoryEnd = computed(() => buffers.value.fps.at(-1)?.ts ?? 0)
 const recordingButtonLabel = computed(() => recording.value
   ? t('tamagotchi.settings.devtools.pages.performance-visualizer.overlay.stop')
   : t('tamagotchi.settings.devtools.pages.performance-visualizer.overlay.record'))
@@ -212,7 +215,14 @@ function resetPosition() {
               </template>
             </span>
           </div>
+          <FpsHistory
+            v-if="metric.key === 'fps'"
+            :samples="buffers.fps"
+            :started-at="fpsHistoryEnd - 10000"
+            :stopped-at="fpsHistoryEnd"
+          />
           <div
+            v-else
             :class="['h-10 overflow-hidden rounded bg-white/5 px-1 py-1', 'flex items-end gap-0.5']"
             aria-hidden="true"
           >
diff --git a/apps/stage-web/src/components/Devtools/fps-history.browser.test.ts b/apps/stage-web/src/components/Devtools/fps-history.browser.test.ts
new file mode 100644
index 000000000..3760f1ba7
--- /dev/null
+++ b/apps/stage-web/src/components/Devtools/fps-history.browser.test.ts
@@ -0,0 +1,48 @@
+import en from '@proj-airi/i18n/locales/en'
+
+import { describe, expect, it } from 'vitest'
+import { render } from 'vitest-browser-vue'
+import { createI18n } from 'vue-i18n'
+
+import FpsHistory from './fps-history.vue'
+
+describe('fps history', () => {
+  it('places a slow frame at its timestamp and keeps the FPS scale above 60 when needed', async () => {
+    const screen = await render(FpsHistory, {
+      props: {
+        samples: [
+          { ts: 900, value: 500 },
+          { ts: 1000, value: 120 },
+          { ts: 1100, value: 60 },
+          { ts: 1800, value: 10 },
+          { ts: 2100, value: 500 },
+        ],
+        startedAt: 1000,
+        stoppedAt: 2000,
+      },
+      global: {
+        plugins: [createI18n({ legacy: false, locale: 'en', messages: { en } })],
+      },
+    })
+
+    // A histogram loses time order. Equal spacing would also hide the 700 ms gap before the slow frame.
+    const chart = screen.getByRole('img', { name: 'FPS history' }).element()
+    expect(chart.querySelector('polyline')?.getAttribute('points')).toBe('0,0 30,30 240,55')
+    await expect.element(screen.getByText('Latest 10', { exact: true })).toBeVisible()
+    await expect.element(screen.getByText('Min 10 / Max 120', { exact: true })).toBeVisible()
+    await expect.element(screen.getByText('-1 s', { exact: true })).toBeVisible()
+  })
+
+  it('shows missing data without inventing a zero FPS sample', async () => {
+    const screen = await render(FpsHistory, {
+      props: { samples: [], startedAt: 1000, stoppedAt: 1000 },
+      global: {
+        plugins: [createI18n({ legacy: false, locale: 'en', messages: { en } })],
+      },
+    })
+
+    await expect.element(screen.getByText('No FPS samples. Enable FPS to collect samples.', { exact: true })).toBeVisible()
+    expect(screen.getByRole('img').element().querySelector('polyline')?.getAttribute('points')).toBe('')
+    await expect.element(screen.getByText('Latest', { exact: false })).not.toBeInTheDocument()
+  })
+})
diff --git a/apps/stage-web/src/components/Devtools/fps-history.vue b/apps/stage-web/src/components/Devtools/fps-history.vue
new file mode 100644
index 000000000..652b0d948
--- /dev/null
+++ b/apps/stage-web/src/components/Devtools/fps-history.vue
@@ -0,0 +1,71 @@
+<script setup lang="ts">
+import type { useDevtoolsLagStore } from '../../stores/devtools-lag'
+
+import { computed } from 'vue'
+import { useI18n } from 'vue-i18n'
+
+const props = defineProps<{
+  samples: Readonly<ReturnType<typeof useDevtoolsLagStore>['buffers']['fps']>
+  /** Bounds use the same performance.now() clock as the samples. */
+  startedAt: number
+  stoppedAt: number
+}>()
+
+const { n, t } = useI18n()
+const history = computed(() => {
+  const samples = props.samples.filter(sample => sample.ts >= props.startedAt
+    && sample.ts <= props.stoppedAt && Number.isFinite(sample.value) && sample.value >= 0)
+  const values = samples.map(sample => sample.value)
+  const maximum = values.length ? Math.max(...values) : 0
+  // Keep a zero baseline and 60 FPS steps so a small fluctuation does not fill the chart.
+  const ceiling = Math.max(60, Math.ceil(maximum / 60) * 60)
+  const duration = Math.max(1, props.stoppedAt - props.startedAt)
+  return {
+    ceiling,
+    latest: samples.at(-1)?.value,
+    minimum: values.length ? Math.min(...values) : undefined,
+    maximum: values.length ? maximum : undefined,
+    // Timestamp spacing preserves the duration of stalls instead of spacing frames equally.
+    points: samples.map(sample => `${((sample.ts - props.startedAt) / duration) * 300},${60 - (sample.value / ceiling) * 60}`).join(' '),
+  }
+})
+</script>
+
+<template>
+  <div :class="['flex flex-col gap-1']" data-testid="fps-history">
+    <div :class="['flex flex-wrap justify-between gap-x-2 text-xs tabular-nums']">
+      <span>{{ t('tamagotchi.settings.devtools.pages.performance-visualizer.history.title') }}</span>
+      <span v-if="history.latest !== undefined">
+        {{ t('tamagotchi.settings.devtools.pages.performance-visualizer.history.latest') }} {{ n(history.latest, { maximumFractionDigits: 1 }) }}
+      </span>
+    </div>
+    <div :class="['flex gap-2']">
+      <div :class="['flex flex-col justify-between text-[10px] tabular-nums opacity-70']">
+        <span>{{ n(history.ceiling) }}</span>
+        <span>{{ n(history.ceiling / 2) }}</span>
+        <span>0</span>
+      </div>
+      <svg
+        viewBox="0 0 300 60"
+        preserveAspectRatio="none"
+        role="img"
+        :aria-label="t('tamagotchi.settings.devtools.pages.performance-visualizer.history.title')"
+        :class="['h-16 min-w-0 flex-1 overflow-visible rounded bg-neutral-500/10']"
+      >
+        <path d="M0 0H300 M0 30H300 M0 60H300" fill="none" stroke="currentColor" stroke-opacity="0.15" vector-effect="non-scaling-stroke" />
+        <polyline :points="history.points" fill="none" stroke="currentColor" stroke-width="1.5" vector-effect="non-scaling-stroke" />
+      </svg>
+    </div>
+    <div :class="['flex justify-between text-[10px] tabular-nums opacity-70']">
+      <span>{{ t('tamagotchi.settings.devtools.pages.performance-visualizer.history.seconds-ago', { seconds: n((stoppedAt - startedAt) / 1000, { maximumFractionDigits: 1 }) }) }}</span>
+      <span>{{ t('tamagotchi.settings.devtools.pages.performance-visualizer.history.end') }}</span>
+    </div>
+    <div v-if="history.minimum !== undefined && history.maximum !== undefined" :class="['text-xs tabular-nums opacity-70']">
+      {{ t('tamagotchi.settings.devtools.pages.performance-visualizer.history.minimum') }} {{ n(history.minimum, { maximumFractionDigits: 1 }) }}
+      / {{ t('tamagotchi.settings.devtools.pages.performance-visualizer.history.maximum') }} {{ n(history.maximum, { maximumFractionDigits: 1 }) }}
+    </div>
+    <div v-else :class="['text-xs opacity-70']">
+      {{ t('tamagotchi.settings.devtools.pages.performance-visualizer.history.empty') }}
+    </div>
+  </div>
+</template>
diff --git a/apps/stage-web/src/pages/devtools/performance-visualizer.vue b/apps/stage-web/src/pages/devtools/performance-visualizer.vue
index da8fdfab5..1d5273014 100644
--- a/apps/stage-web/src/pages/devtools/performance-visualizer.vue
+++ b/apps/stage-web/src/pages/devtools/performance-visualizer.vue
@@ -7,6 +7,8 @@ import { storeToRefs } from 'pinia'
 import { computed } from 'vue'
 import { useI18n } from 'vue-i18n'
 
+import FpsHistory from '../../components/Devtools/fps-history.vue'
+
 import { useDevtoolsLagStore } from '../../stores/devtools-lag'
 
 const { n, t } = useI18n()
@@ -152,6 +154,11 @@ function metricDescription(metric: typeof metricControls.value[number]) {
         <span>{{ t('tamagotchi.settings.devtools.pages.performance-visualizer.metrics.long-task.label') }}: {{ n(lastRecording.samples.longtask.length) }}</span>
         <span>{{ t('tamagotchi.settings.devtools.pages.performance-visualizer.metrics.memory.label') }}: {{ n(lastRecording.samples.memory.length) }}</span>
       </div>
+      <FpsHistory
+        :samples="lastRecording.samples.fps"
+        :started-at="lastRecording.startedAt"
+        :stopped-at="lastRecording.stoppedAt"
+      />
     </section>
 
     <div :class="['text-xs text-neutral-500 dark:text-neutral-400']">
diff --git a/packages/i18n/src/locales/en/tamagotchi/settings.yaml b/packages/i18n/src/locales/en/tamagotchi/settings.yaml
index 596a5a681..d785dc99c 100644
--- a/packages/i18n/src/locales/en/tamagotchi/settings.yaml
+++ b/packages/i18n/src/locales/en/tamagotchi/settings.yaml
@@ -319,7 +319,7 @@ devtools:
       metrics:
         fps:
           label: FPS
-          description: Frames per second during the last 10 seconds.
+          description: Animation frame rate during the last 10 seconds. Each sample is 1000 divided by the frame interval in milliseconds.
         frame-duration:
           label: Frame time (ms)
           description: Time between animation frames during the last 10 seconds.
@@ -335,6 +335,14 @@ devtools:
         title: Last recording
         duration: Duration {duration} ms
         limit: Recording stops after 60 seconds.
+      history:
+        title: FPS history
+        latest: Latest
+        minimum: Min
+        maximum: Max
+        seconds-ago: '-{seconds} s'
+        end: 0 s
+        empty: No FPS samples. Enable FPS to collect samples.
       overlay:
         title: Performance
         move: Move performance overlay
diff --git a/packages/i18n/src/locales/zh-Hans/tamagotchi/settings.yaml b/packages/i18n/src/locales/zh-Hans/tamagotchi/settings.yaml
index beaf08f07..79e45564d 100644
--- a/packages/i18n/src/locales/zh-Hans/tamagotchi/settings.yaml
+++ b/packages/i18n/src/locales/zh-Hans/tamagotchi/settings.yaml
@@ -68,7 +68,7 @@ devtools:
       metrics:
         fps:
           label: FPS
-          description: 最近 10 秒内的每秒帧数。
+          description: 最近 10 秒内的动画帧率。每个样本为 1000 除以帧间隔（毫秒）。
         frame-duration:
           label: 帧时间（毫秒）
           description: 最近 10 秒内动画帧之间的时间。
@@ -84,6 +84,14 @@ devtools:
         title: 上次录制
         duration: 时长 {duration} 毫秒
         limit: 录制会在 60 秒后停止。
+      history:
+        title: FPS 历史
+        latest: 最新
+        minimum: 最低
+        maximum: 最高
+        seconds-ago: '-{seconds} 秒'
+        end: 0 秒
+        empty: 暂无 FPS 样本，请启用 FPS 采集。
       overlay:
         title: 性能
         move: 移动性能浮窗