iTrash: What resolution are you running at? With the higher resolution patches and the software renderer, I wouldn't be surprised if that's just super slow.
Edit: Just tried it myself on 2560x1440: Yes the software renderer is VERY slow at that resolution.
Just use the hardware renderer, you're gonna have better picture quality and it'll run faster.
If the hardware renderer is not avaiable, install dgVoodoo2 in the S4/Exe directory (ddraw.dll, d3dimm.dll) to fix it.
the highest I can do it at is 1200 PX and it as slow as a slide show. it doesnt mater if its at hardware or software rendering