I've gotten amazing performance boost on my 7 year old XP machine by doing the following:

- Decompress the RTs that I use
- Enable the +/- RealTracks option (the newer RTs don't have these)
- Decompress the RDs that I use
- Defragment the RD/RT drive(s)

A 4 minute song containing two RTs completely generates in about 8 seconds. Before, it took about 30 seconds. You can speed this up further by Freezing the RTs. Granted this will gobble up disk space but, if available, well worth it.

Speed up generation and tempo stretching RT options are disabled.

R