We've been hacking on ChalkBoard, and there is this import optimization that we've added to our version of OpenGLRaw. It make ChalkBoard run almost twice as fast. The problem was the conversions between GLfloat and regular floats was using realToFrac, which uses fromRational . toRational. This can be fixed by using the GHC RULES. (inside the GHC specific part of includes/CTypes.h) #define GHC_RULE(N,R) {-# RULES "N" R #-} #define FLOATING_TYPE(T,C,S,B) \ newtype T = T B deriving (ARITHMETIC_CLASSES, FLOATING_CLASSES); \ INSTANCE_READ(T,B); \ INSTANCE_SHOW(T,B); \ INSTANCE_TYPEABLE0(T,C,S) ; \ GHC_RULE(realToFrac/a->T,realToFrac = \x -> T (realToFrac x)) ; \ GHC_RULE(realToFrac/T->a,realToFrac = \(T x) -> realToFrac x) (the last two lines are the new lines) We've asked for this change to be added to the office release of OpenGLRaw. Cheers! Andy & Kevin ---- Andy Gill, <andygill@ku.edu> Assistant Professor The University of Kansas, EECS Department Information and Telecommunication Technology Center