Significant lag spikes in N64 game play when using fast forward

[RobertMenke]

I've observed that fast-forwarding game play will often cause significant lag spikes (video attached). While I imagine rendering performance is largely the responsibility of the mupen emulator, I wonder if any of the following solutions might improve the player experience:

1. Avoid incrementing the frame counter when it reaches some threshold (although I do see that the mupen renderer already avoids executing the frame when the counter is >= 10 https://github.com/OpenEmu/Mupen64Plus-Core/blob/9f0d2f35b0fd2d16ea79194a0d0ad22d1529f274/MupenGameCore.m#L424).
2. Provide users with a fast-forward rate slider in the gameplay settings menu that will ultimately influence the adjustedRate in the game loop https://github.com/OpenEmu/OpenEmu-SDK/blob/3d2214e328668697ce771d657a05076455ddc899/OpenEmuBase/OEGameCore.m#L307.

Happy to attempt to put a PR together if we can agree on a path to mitigating the issue. Thank you!

https://github.com/user-attachments/assets/845898ad-e1bc-4cdf-aeae-53617ede3560