I am not the author of the 1.2 version with RTG on Aminet.
I added RTG mode for the Vampire team that I never got around to releasing almost 2 years ago now. I just added it to the zone if you wanted to try that version and see if its any better in RTG.
launch it with
strife.exe -cgx
also -novoice will start the game without speech and will enable subtitles in the game
let me know if performance is any better with RTG
thanks!
http://eab.abime.net/zone/strife-rtg.lha