[Impeller] Impeller (OpenGLES) is far slower than Skia on PowerVR Rogue GE8320 (MT6765) — 100% of scroll frames late and raster-bound, Flutter 3.47.1 #193009

Related to #192364, but a different GPU vendor and — importantly — the OpenGLES backend rather than Vulkan, so the "poorly implemented Vulkan driver" hypothesis raised there does not cover this case. @gaaclarke asked on that issue whether the regression reproduces on another device; this is that data point.

Steps to reproduce

1. Build a release APK of a portrait phone app whose main screen is a scrolling column of translucent cards over a full-screen background. The background is four stacked full-screen layers: a linear gradient, a JPEG (~900×1350, BoxFit.cover), a flat scrim Container, and a second linear gradient. No BackdropFilter, no blur, no ShaderMask, no custom shaders. The cards are alpha fill, not blur.
2. Install on an Infinix X6532C (MediaTek MT6765, PowerVR Rogue GE8320, OpenGL ES 3.2, Android 14, armeabi-v7a, 720×1600 running its 60 Hz mode).
3. Drive an identical scripted scroll so the input is the same at every build:

for i in $(seq 1 12); do
  adb shell input swipe 360 1250 360 450 220
  adb shell input swipe 360 450 360 1250 220
done

4. Collect frame timings in-app from SchedulerBinding.instance.addTimingsCallback, counting a frame late when FrameTiming.totalSpan exceeds 16.667 ms, and separately counting frames whose buildDuration or rasterDuration alone exceeds it.
5. Add the opt-out to AndroidManifest.xml, rebuild, and run the same script again:

<meta-data
    android:name="io.flutter.embedding.android.EnableImpeller"
    android:value="false" />

Expected results

Impeller performs at least as well as Skia, so that removing the opt-out — which is deprecated, and which the engine warns about on every launch — is safe.

Actual results

Under Impeller, every single frame of a scroll is late, and it is raster-bound. Same APK contents, same device, same scripted scroll, three consecutive runs alternating the renderer:

Mean frame span under Impeller was 32.8 ms — about 30 fps on a 60 Hz panel — against a smooth result on Skia from identical Dart code.

Mean buildDuration was 1.5 ms in every run, on both renderers, so the framework side and the widget tree are not involved. The entire difference is raster.

The engine selects the GLES backend on this device on its own; this is not a forced configuration. Relevant log line:

[IMPORTANT:flutter/shell/platform/android/android_context_gl_impeller.cc(104)] Using the Impeller rendering backend (OpenGLES).

Notes

• This is a release build. Unlike [Impeller] Impeller is significantly slower than Skia on Adreno 702 (QCM2290) — 3.5x worse raster, Flutter 3.47.2 #192364, no profile-mode comparison is offered, because the Impeller profile-mode engine artifacts could not be fetched here; everything above is release-to-release.
• Wrapping the static four-layer background in a RepaintBoundary moved mean raster only from 21.7 ms to 20.6 ms — inside the noise between sessions. So the cost does not appear to be re-rasterising a cacheable background, and I could not find an application-side mitigation that recovered the frame rate. Disabling Impeller was the only thing that worked.
• PowerVR Rogue GE8320 on MT6765 is a very common low-end Android part, and GLES-only devices are the floor of the Android market. Together with [Impeller] Impeller is significantly slower than Skia on Adreno 702 (QCM2290) — 3.5x worse raster, Flutter 3.47.2 #192364 (Adreno 702, Vulkan), that is two different GPU vendors and two different backends showing Impeller materially slower than Skia on low-end hardware, which argues against an e: device-specific reading.
• The practical concern is the deprecation: when the opt-out is removed, an app in this position has no mitigation left in its own hands.

Flutter Doctor output

Flutter 3.47.1 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 6655482ec0 • 2026-08-19
Engine • hash 11d79658c444477b06513d32b52c8c4ccb7276b0 (revision 5d53178869) • 2026-08-18
Tools • Dart 3.13.1 • DevTools 2.60.0

Device, for completeness:

ro.product.model      Infinix X6532C
ro.build.version.release  14
ro.product.cpu.abi    armeabi-v7a
ro.hardware           mt6765
SurfaceFlinger GLES   Imagination Technologies, PowerVR Rogue GE8320,
                      OpenGL ES 3.2 build 1.15@6070602