This tool helps you convert a .AIR file with normal timings to Turbo timings given a frameskip value. Remember: you must grab the timings in true normal (in VSav, you have to set this through the game config menu, since the default "normal" is actually Turbo 1. I believe this is also the case for SFA3).
In general you'll most likely use 3 (1 in 3 frames) or 4 (1 in 4 frames)
In case you're wondering about the values CvS2 and CFJ use (highlighted numbers are the ones you'll want to use for the SKIP_FRAME value:
1 star - No frameskip[/li]
2 star - 1 in 5 frames[/li]
3 star - 1 in 4 frames[/li]
4 star - 1 in 3 frames[/li]
5 star - 1 in 2 frames[/li]
These will vary from game to game, so it is your responsibility to know which value to use. Do not use any value lower than 2. Requires Python 3.