F-Zero GX 3rd stage sudden slow down

[username]

Hello,

When playing F-Zero GX on the third-course, the game speed suddenly drops to 60% although of my laptop ability to handle the first two courses, with resolution reaching 8x native 5k, at full speed 100%. I have tried to reduce the resolution to native but the speed stayed at the range between 60% and 70%. I do not know why it slows down at the third stage of the ruby cub.

Note: I am using Asynchronous (Ubershaders) and have selected compile shaders before starting.

To reproduce the issue:
1) run the NTSC U version of F-Zero GX
2) select Grand Prix
3)  Ruby cup
4) select a character
5) win the first two course
6) now you are in the third-course where the speed drops 

[username]

This is the third course

[Craftyawesome]

This problem is noted on the wiki page https://wiki.dolphin-emu.org/index.php?title=F-Zero_GX#Heat_Effect.2FBlur
It notes that vulkan runs faster and that enabling Skip EFB Access from CPU will stop the problematic effect entirely.

Unrelated, but IIRC dolphin doesn't have a good downscaler when running at a higher resolution than your monitor. Putting the internal resolution to match your monitor and increasing anti aliasing should get a better picture. Maybe this has changed, but this should work better.