OpenGL performance is extremely low. Making use of VBOs for everything could possibly help here. glBegin/End shit needs to go.
Performance seems to take a nosedive beyond 480p resolution.
Reviving jwzgles stuff could possibly be a good idea, or move to gl4es.
JFDuke3D Polymost runs wonderfully at 1080p, wonder what it's doing that makes it run so much better?
Changing screen resolution permanently degrades performance to sub-1fps.
Intro animations and title screen palettes are totally screwed up.
There's something wrong with either multiplication or division operations in CON, because the screen shake code in StrikerDM causes the camera position values to get extremely fucked up with excessively large numbers.