(after note) I did notice a few lag spikes during your loading sequences, however the races were fine

Are you using a PAL or an NTSC version of the game? and which version of dolphin? I use 4.0-6554 and just default settings ingame... it might have to do with Wide Screen mode but i HIGHLY doubt it

I use Dolphin... i was constantly running at the required FPS. if you have lag that's kind of your problem