Significant FPS drop in MediaElement software rendering on x64 compared to x86 in .NET 8/9 possibly all

### Description

WPF app with 2 windows playing same video via MediaElement.
Software rendering forced
x86 builds reach ~30 FPS
x64 builds reach ~9 FPS

Hardware rendering fixes FPS but has memory leaks on Intel GPUs

FPS measured with CompositionTarget.Rendering event handler

### Reproduction Steps

https://github.com/MartinSnaparazzi/VideoSample/

Run this sample WPF project and swap between

x64
and
x86
in the csproj file

observe the difference in video playback

### Expected behavior

Expect to see similar performance between x64 and x86 for such a small sample project

### Actual behavior

x86 runs a lot faster

### Regression?

_No response_

### Known Workarounds

_No response_

### Impact

_No response_

### Configuration

_No response_

### Other information

_No response_