Gpw is very slow on modern machine and i've been trying to find a way to fix it.
There is the Ddraw files that's shared around here but it crash my game whenever i used it. (some people also have the same issue)
After some digging, i've managed to find something that worked. (at least for me, i'm not 100% sure for others)
Well its a different ddraw.dll which doesn't crash my game that i found here:
community.pcgamingwiki.com/files/file/2069-ddrawcompatDownload the latest verison and place ddraw.dll at GPW main directory.
After that then use the speedup tool from here:
grandprixworld.narod.ru/gpw_download.html (Grand Prix World SpeedUp Patch)
Place it in the Save file inside GPW main directory.
Run it and select the speed you want, then you can close it and run the game.
The speed up is not yet active, you need to go ingame to the Game Options,
3d Graphics, and then click minus once on the game speed.
(example: you set the speedup at 500%, ingame you reduce it from 500% to 499%)
Races now should be lightning fast.
This worked for me using Windows 10 and the 1.03 patch. I haven't tested it with any Season mods.
Thanks for people here keeping this game alive!