Rogue Squadron is both an EFB2RAM game (GPU intensive) and an MMU game (CPU intensive), making it pretty much the most intensive thing you can play in Dolphin. In terms of raw CPU requirement, it probably requires more CPU power than any other Gamecube game, and even Virtual Console games, so a non-Intel chip will suffer.
Possible ways to make it faster:
1. Turning off EFB2RAM and EFB Access From CPU (in the graphics settings) will break some effects, but give you more speed.
2. Rogue Squadron is a variable framerate game, so reducing the emulated CPU clock (in the advanced settings) can lower the game's FPS to make it use less CPU and be more able to run at full speed. You may have to drop it quite a lot though; don't be surprised if you need to go to 50% or lower to get a major effect.
3. If you disable the music, DSP HLE can be used (HLE is bugged with the music currently, from what I recall). This could save some CPU.
... but there's no guarantees. My Ivy Bridge @ 3.4Ghz could barely play it at full FPS in some levels even with a bit of underclocking.
Possible ways to make it faster:
1. Turning off EFB2RAM and EFB Access From CPU (in the graphics settings) will break some effects, but give you more speed.
2. Rogue Squadron is a variable framerate game, so reducing the emulated CPU clock (in the advanced settings) can lower the game's FPS to make it use less CPU and be more able to run at full speed. You may have to drop it quite a lot though; don't be surprised if you need to go to 50% or lower to get a major effect.
3. If you disable the music, DSP HLE can be used (HLE is bugged with the music currently, from what I recall). This could save some CPU.
... but there's no guarantees. My Ivy Bridge @ 3.4Ghz could barely play it at full FPS in some levels even with a bit of underclocking.