FIXED!!! Turn SpeedStep back on!
In my case, I installed Rogue Squadron 3D 1.3 on an old Dell Latitude D410 laptop with onboard Intel graphics. I was tickled to death that RS did not have the crash after every mission problem on this system. However, everything was twice as fast (or more) and unplayable. After not finding much useful info online I kept poking around and noticed Windows XP (sp3) was reporting my CPU speed as 1.6 GHz AND 800 MHz on the My Computer properties page. Hmmm... if the system was reporting CPU speed wrong, that would explain a few things. lol
I went back into the BIOS and turned SpeedStep back on - I had turned it off when trying to troubleshoot overheating problems - Booted back into Windows and Voila! CPU speed shows up as 1600 MHz, AND Rogue Squadron runs FLAWLESSLY!