I've always had a much smoother experience with nGlide. Have you tried other glide wrappers?

Can you recommend one? Also I have to warn you, if I go that route I'm likely to pester you with really stupid setup questions. :P

Sure. :) The main two that I've seen people using around here are nGlide and DGVoodoo, both of which work with TR1. I've personally found nGlide to work better, but I think it's largely dependent on your system specs. DGVoodoo is more intricately configurable, if that's your thing.

nGlide
http://www.zeus-software.com/downloads/nglide

DGVoodoo
http://dege.freeweb.hu/

I'm not sure if this helps, but i played TR1 late last year and the latest installer that i downloaded automatically installed with nGlide already setup and working. Is it possible you're using an older installer?

Edit: Okay i just realized you didn't specify the GOG version, so maybe you're trying to run a disc version in which case you would need info.

Edit2: after checking, it seems i remembered it wrong, the GoG version doesn't install nGlide, it installs OpenGlide emulation which seems to work okay- well i played the entire game with it anyway.