Wow, it took me a while I realized you've changed your nick, Azura
Ninnghizhidda, I don't know if you're just having bad luck or something else, but I'll give some of
my recommendations that may help.
First and foremost - don't use any of those "registry tweaks" - they usally just don't have any effect. I had very similar system configuration a while back and I ran UT successfully with great performance.
You did't mention exactly what Direct3D9/OpenGL renderer versions you used so I assume they were latest from here:
http://www.cwdohnal.com/utglr/
Be sure to set your FrameRateLimit to something like 60...80 and not exceed 100 because otherwise it tends to give you some graphical glitches (especially in particle effects & animations). Configure your RefreshRate to match your display settings, experience has shown it affects overall smoothness (e.g. if your LCD is set to 75Hz and UT is (auto)configured to run at 60Hz, game feels choppier, of course it varies on different displays)
I'll post my current INI settings, but since you're after performance and not eyecandy you can set most of those options
false. More information about each setting here:
http://www.cwdohnal.com/utglr/settings.html
Code:
[OpenGLDrv.OpenGLRenderDevice]
ZRangeHack=True
NoAATiles=True
NumAASamples=4
UseAA=True
MaskedTextureHack=True
SmoothMaskedTextures=False
SceneNodeHack=True
FrameRateLimit=62
SwapInterval=0
UseFragmentProgram=True
UseVertexProgram=True
UseCVA=True
UseMultiDrawArrays=True
TexDXT1ToDXT3=False
DynamicTexIdRecycleLevel=100
CacheStaticMaps=False
UseTexPool=True
UseTexIdPool=True
UseSSE2=True
UseSSE=True
BufferTileQuads=True
SinglePassDetail=False
SinglePassFog=True
ColorizeDetailTextures=False
DetailClipping=False
DetailMax=2
RefreshRate=75
MaxTMUnits=0
NoFiltering=False
MaxAnisotropy=16
UseTNT=False
Use16BitTextures=False
UseS3TC=True
UseAlphaPalette=True
UseTrilinear=True
UsePrecache=True
ShareLists=False
UsePalette=True
UseMultiTexture=True
UseBGRATextures=True
UseZTrick=False
MaxLogTextureSize=8
MinLogTextureSize=0
OneXBlending=False
GammaCorrectScreenshots=False
GammaOffsetBlue=0.000000
GammaOffsetGreen=0.000000
GammaOffsetRed=0.000000
GammaOffset=0.000000
LODBias=-0.500000
DetailTextures=True
DescFlags=0
Description=ATI_GPU
HighDetailActors=True
Coronas=True
ShinySurfaces=True
VolumetricLighting=True