[bjames]

Running through Softwindows 95, it’s dead slow, couple frames per second at best.  Even shut down windows into DOS mode thinking it will allocate all windows resources to DOS, but still slow.   I set the Softwindows memory to max 32mb.

I used to run this on a penguin 200pro through windows 95 AutoCAD machine back in the 90s and it was pretty fast.

Any advice?

[Raion]

My suggestion would be to compile it for IRIX directly. AFAIK, zdoom and some other doom engines can run heretic, and you can probably compile zdoom or gzdoom on IRIX easily. I stopped last time I looked because they used glib and gtk