Periodic frame rate drops (60→54 FPS; 6-10 consecutive frames every 5 seconds) with CoreCLR on .NET 11: Regression from Mono on .NET 10

[janne-hmp]

Android framework version

net11.0-android (Preview)

Affected platform version

Android 16

Description

We are developing a real-time roguelike game (GnollHack) using .NET MAUI with SkiaSharp (SKGLView) for rendering on Android. The game targets 60 FPS and achieves this consistently on .NET 10 with the Mono runtime.

As per the post by @davidortinau last week, we tested .NET MAUI 11 Preview 6 on Android to see how it compares with Mono Runtime in .NET 10. After upgrading to .NET 11 Preview 6 (which uses CoreCLR exclusively on Android), we observe periodic (every 5 seconds or so) frame rate drops from 60 FPS to approximately 50–54 FPS (6-10 consecutive frames drop every 5 seconds or so), causing severe stutters in the game and making the game to feel continuously very jerky. These drops occur at regular intervals regardless of scene complexity, even on screens with very little drawing. The drops are clearly visible as jerkiness during gameplay.

This appears to be a performance regression introduced by the Mono-CoreCLR transition on Android.

If @jonathanpeppers or someone else already know a solution working for this in .NET MAUI 11, please let me know.

Expected Behavior

Consistent 60 FPS rendering, matching .NET 10 (Mono) performance.

Actual Behavior

Frame rate periodically drops to 50–54 FPS at regular intervals, causing visible jerkiness. The drops occur:

• From the very start of the application
• Regardless of scene complexity (even with minimal drawing)
• At consistent, periodic intervals

Environment

• .NET SDK: 11.0.100-preview.6 (or later)
• Runtime: CoreCLR (Mono no longer available in Preview 6+)
• Platform: Android (arm64)
• Rendering: SkiaSharp SKGLView (OpenGL ES)
• Target FPS: 60
• Device: (Insert your test device and Android version here)
• Comparison baseline: .NET 10 with Mono runtime, consistent 60 FPS, no drops

Additional Context

• The application is a complex roguelike game with native C libraries linked via P/Invoke, FMOD audio, and multi-layer tile rendering.
• The frame drops are not correlated with scene complexity, suggesting the cause is runtime-level periodic work (GC, thread pool, diagnostics, or other background activity) rather than application code.
• <UseMonoRuntime>true</UseMonoRuntime> is no longer supported in .NET 11 Preview 6, so we cannot fall back to Mono to verify the regression on the same SDK version.

Steps to Reproduce

1. Create a .NET MAUI application targeting net11.0-android with a SkiaSharp SKGLView rendering at 60 FPS.
2. Build and deploy to an Android device.
3. Observe periodic frame rate drops from 60 to ~54 FPS at regular intervals.
4. Compare with the same application targeting net10.0-android (Mono runtime); no such drops occur.

Did you find any workaround?

No, see attempted mitigations:

Setting	Result
DOTNET_TieredCompilation=0	No improvement
DOTNET_GCGen0MaxBudget=8000000 (128 MB)	No improvement
DOTNET_gcServer=0 (Workstation GC)	No improvement
Default CoreCLR settings (no tuning)	Same periodic drops

Relevant log output

[janne-hmp]

I made a test app to show the periodic drop in FPS: https://github.com/hyvanmielenpelit/Net11FPSBenchmark Here it happens, every 10 to 20 s or so. It has various extra switches to test things, and also the iOS issue separately, but it currently best works for demonstrating this problem on Android. There is also a script to alternate between .NET 10 and .NET 11. In .NET 10 you can observe a much smoother FPS behavior.

[jonathanpeppers]

If you need to test UseMonoRuntime=true to compare .NET 11 side-by-side, you can set _DisableCheckForUnsupportedMonoMobileRuntime=true:

• https://github.com/dotnet/sdk/blob/78b84df89821f3ec40482115ba9a7c41cb624f08/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.TargetFrameworkInference.targets#L142-L148

Would be interesting to know if UseMonoRuntime=true + _DisableCheckForUnsupportedMonoMobileRuntime=true solves the issue in the latest release (.NET 11 Preview 6).