Well, this all left me intrigued, so I fired up FRAPS and made some benchmarks.
I discovered this: On my laptop the FPS in Enhanced is limited by the CPU, on Premium it's limited by the GPU and I lose about 30 FPS in 1280x800.
Just for reference, my laptop has a 2.2GHz Core 2 Duo (T7500), a Geforce 8600M GT and 4GB of RAM.
I used a 59 second song, played in Double Vision Casual which resulted in 224 traffic (which is practically all downhill on Casual).
Benchmarks were started at the beginning of the fly-in and ended as the screen darkens as you enter the squid I mean, giant swirling space vagina.
1280x800:
- Enhanced averaged 83.669 FPS
- Premium averaged 50.663 FPS
1680x1050:
- Enhanced averaged 86.340 FPS
- Premium averaged 44.095 FPS and 43.690 FPS (I accidentally made two runs when I forgot to change one of the settings).
Anti-aliasing was off for all benchmarks, as was VSync. All tests were taken in fullscreen on Win7 x64 and Audiosurf was restarted in between each run with the settings changed before starting the game using the ini files.
What does it tell us? Nothing we didn't already know I don't think, Premium has a much heavier graphics cost than Enhanced and Audiosurf is heavily limited by CPU speed on slower machines. That's core speed, dual or quad cores will make little difference to Audiosurf's performance.
Also, we're not really hitting fill-rate issues, otherwise the 1680x1050 performance would be MUCH lower than the 1280x800, which indicates to me it's actual shader execution time that's causing the speed issues.
I did get better performance than I expected from Premium, but it's very jerky and juddery every time you make a large match, meaning it would be difficult to play on faster tracks.
I've attached the full benchmark data FRAPS generated if anyone wants a look. It's not that interesting, the most useful values are the averages I quoted above.
