Before 469 it was more the updated video drivers that came with the inis that made the difference, disabling mouse smoothing, using direct input, making sure vsync was off, disabling the prettier graphical effects for better fps, there was this 444 texture setting that worked with old cards but that doesn't work anymore that made textures pop a bit more, oneXblending enabled, negative lodbias for sharper details at further distances(using resolution scaling in ICB11 makes it look much better you just have to use integer values like 1,2,3).
Nowadays it's pretty much just a fresh install, 469e patch, select d3d11, icb11, or icb9 for lowest latency on windows, or opengl for best colours, disable gibs and decals(mainly for instagib and open maps causing fps drops), disable mouse smoothing, oneXblending.
Or just use the Linux 64bit build for a significant performance increase all round compared to 32bit windows, it's much easier to install since 469 patch, pretty much just drop the linux files over a windows install and start the game from the /ut/system64/ut-bin-64.sh to play UT natively on Linux without needing wine or something else. Only downside is that you run in physics issues at super high fps(same as windows) so you will have to limit fps to 500-750fps.
