Severe FPS regression after replacing OpenGL43 with ARB_compute_shader on Samsung M12

[z-xp-5]

Describe the bug
On my Samsung M12 device, there is a severe performance regression after the
OpenGL43 rendering path was removed and replaced with the new
"Incomplete ARB_compute_shader" extension in MobileGlues.

In older versions, enabling OpenGL43 (even though it was incomplete) allowed
the same game, with the same shader and identical settings, to run at a stable
~30 FPS. After updating to the latest MobileGlues version and enabling
ARB_compute_shader, performance drops dramatically to ~6 FPS, making the game
effectively unplayable.

This strongly suggests that the compute-shader-based rendering path is
significantly slower than the previous OpenGL43 path on this hardware.

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To Reproduce

1. Use a Samsung M12 (Exynos 850, Mali-G52 MC2) running Android 13
2. Launch the game using Zalith Launcher
3. Minecraft 1.21.11 with Fabric 0.18.4
4. Enable Iris Shaders and use:
   z1[Amethyst Shaders] AmethystShaders_2.4
5. Use the same mods and identical in-game settings
6. Older MobileGlues version:
   • Enable OpenGL43 → ~30 FPS
7. Latest MobileGlues version:
   • Enable "Incomplete ARB_compute_shader" → ~6 FPS
8. No other settings were changed between tests

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Expected behavior

• Performance should be comparable to or better than the old OpenGL43 renderer
  OR
• OpenGL43 should remain available as a legacy / fallback option for devices
  where it performs better.

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Actual behavior

• FPS drops by more than ~80%
• Severe stuttering and unplayable performance

---

Config

Device & Software:

• Device: Samsung M12 (A12034M)
• OS: Android 13
• SoC: Exynos 850
• GPU: Mali-G52 MC2
• Launcher: Zalith Launcher
• MobileGlues Version: Latest
• Minecraft Version: 1.21.11
• Mod Loader: Fabric 0.18.4

Shaders & Mods:

• Shaderpack: z1[Amethyst Shaders] AmethystShaders_2.4
• Mods list:
  • Alan's Unified UI v0.2.2
  • Chunky-Fabric 1.4.55
  • Fabric API 0.141.3+1.21.11
  • FerriteCore 8.2.0 (Fabric)
  • ImmediatelyFast 1.14.2+1.21.11
  • Iris Shaders 1.10.5+mc1.21.11
  • Sodium 0.8.4+mc1.21.11

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MobileGlues Settings (from UI / config.json)

• Use ANGLE as OpenGL ES driver: Enabled
• Max GLSL Cache Size: 128 MB
• MultiDraw Emulation: Auto
• Enable Incomplete 'ARB_compute_shader' Extension: Enabled
• Recommended 'timer_query' Extension: Disabled
• Advanced 'direct_state_access' Extension: Disabled
• Custom target OpenGL Version: Disabled
• ANGLE Depth Clear Workaround: Disabled
• Built-in FSR1: Disabled

config.json:
{
"enableANGLE": 3,
"enableNoError": 1,
"enableExtTimerQuery": 0,
"enableExtComputeShader": 1,
"enableExtDirectStateAccess": 0,
"maxGlslCacheSize": 128,
"multidrawMode": 0,
"angleDepthClearFixMode": 0,
"customGLVersion": 0,
"fsr1Setting": 0
}

---

Logs
latest.log:
Initializing MobileGlues ...
MG_DIR_PATH = /sdcard/MG

[MobileGlues] Setting: enableAngle = true
[MobileGlues] Setting: ignoreError = 0
[MobileGlues] Setting: enableExtComputeShader = true
[MobileGlues] Setting: enableExtTimerQuery = false
[MobileGlues] Setting: enableExtDirectStateAccess = false
[MobileGlues] Setting: maxGlslCacheSize = 128
[MobileGlues] Setting: angleDepthClearFixMode = 0
[MobileGlues] Setting: customGLVersion = 4.0.0
[MobileGlues] Setting: fsr1Setting = 0

EGL initialized successfully
OpenGL ES Version: OpenGL ES 3.2.0 (320)

Detected GL_EXT_multi_draw_indirect!
multidrawMode = Auto → MultidrawIndirect (Auto detected)

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Screenshots

• Attached: MobileGlues settings screen
• Attached: Zalith Launcher mod list

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Additional context
The issue consistently occurs when enableExtComputeShader is enabled.
The previous OpenGL43-based path (now removed) delivered significantly better
performance on the same hardware under identical conditions.

This appears to be a renderer-specific performance regression rather than a
general configuration, mod, or driver issue. Restoring OpenGL43 as a legacy
option or optimizing the ARB_compute_shader path for lower-end GPUs (such as
Mali-G52) would greatly improve usability on such devices.

I am willing to provide additional logs, perform further tests, or help with
A/B comparisons if needed.