So far experiments continue with SWAT 4 performance issues. Deeper testing has shown that it is no longer connected to graphical issues, not when running on my current hardware/driver config; nice to be able to max out the graphics online *and* in single player.
What happens is periodically when moving through an area, I get a stutter-lag-warp like motion: as if the whole game stopped spinning and then suddenly unlocked. The only consistency I've noticed is it happens when entering a region of the map that I have not been in previously—or have not been in for a while. One thought is that perhaps it occurs when the cache must be updated with stuff that has already been moved out of the games memory cache. My machine has RAM to burn so I have been testing the game with various cache sizes, but don't honestly expect any positive result. On modern machines, cache size shouldn't matter to much with the Unreal Engine 2.x lol.
Atm I'm defragging a few disks, maybe that might help a little. I don't know if it is just the much greater frequency of crashes with Windows XP, or that NTFS really sucks that much worse then FreeBSDs UFS2 system. But for one reason or another, my windows file systems always end up very highly fragmented. Although on the upside, unlike Win32: FreeBSD does kind of encourage you to fsck afterwards hehe.
Hopefully my experiments will yield some fruit, and I can stop warping all over the place lol.