Delphi optimization

I am trying to code a volume renderer, to display computed tomography data. I have been struggling with it for some weeks now and have managed to produce a ray casting procedure, but it is still very slow (I will describe this in another posting later on). Searching the Internet I have come across some rather advanced (for me at least) optimization strategies for Delphi, which may interest some of you. Use Google to look for 'CodingForSpeedInDelphi.doc' by Dennis Christensen. It mentions VTune, a software by Intel that can be used to check for cache misses, cache thrashing and other esoteric stuff. Intel gives the software for a trial period of one month, but be prepared for a very long download time (size is about 200Mb!). I haven't tried it yet, but meantime I have applied some of the advice in the Christensen document (and in a ppt file, also found be Google: singlepe_optimize.ppt). By re-ordering some 'for' loops and substituting divisions by multiplications of the reciprocal, I have managed to shave off approximately 1 full second from the ray casting procedure (which amounts to 10% of the total). Now, if only I could get rid of those annoying Out of Range errors!