Almost the same happened to me, except I upgraded from a Voodoo 2 to a GeForce 256. Problem seems to be that nVidia chipsets need
more RAM than 3dfx do, which leads to the solution I´ve chosen: upgrading from 128 MB RAM to 256. No swapping to harddrive anymore. My other computer is without memory for ´bout a month now...

The "problem" is that UT was written predominantly for Glide, and D3D and OpenGL are less efficient.
 
The easy solution is to either:
 
Buy a Voodoo2 SLI (I get 60FPS in UT)
Buy more memory.
 
 
 
 
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SuperMicro P6DBS (dual UW-SCSI) BIOS 2.2, 2*Celery 300a @ 450Mhz, 384MB PC100 RAM
SCSI-A=4.3Gb+9Gb, SCSI-B=Tosh32x CD-ROM, Yamaha4416 CD-RW, Iomega ZIP100, IDE1=4.3Gb
IBM EtherJet 10/100 NIC PCI + Nortel ADSL "modem"
Matrox G400 DH 32Mb AGP + Quantum3D Voodoo2 SLI PCI (CL TNT1 AGP on a shelf)
SoundBlaster Live PCI (not Value)
Win2K build 2195 Retail (not 120-day eval)

UT use a lot of cache with all videocards.

Give this a try
3D SPOTLIGHT - Unreal Tournament Tweak Guide http://www.3dspotlight.net/tweaks/ut/index.shtml

Kind of a weird answer, but get another hard drive and more memory. Move the page file to the other hard drive and make sure it is on a different IDE controller. Sound easy, doesnt it. Sure cost alot though.

I changed from a Banshee to a TNT2 also, it does seem a bit slower...
 
Which API do you guys use for TNT2s? Glide or OpenGL?
 
Any idea how to show your fps or calculate it?

Glide all the way on an 8 meg voodoo2. Runs perfect. Direct3d doesnt look as that much different when running on a TNT 1 card. Maybe a little better, but stutters more than the glide version. To get a FPS count, at the intro movie, hit (really hard!) the ~ key and type in timedemo 1 and then bash the enter key. After a few cylcle, beat the ~ key to bring the menu down again to see you FPS rates for the city intro movie. >

Is anyone using v2 SLI with UT and Win2k? I get random lockups, wondering if there might be some setting tweaks i can use... other games (half life, homeworld, eq work ok.... everyonce in awhile will crash, but not as often as UT).

I'm running UT on W2K with V2-SLI, and it's rock solid. No tweaks, just installed and ran. Maybe it's an issue with sound card drivers?
 
Oh, and there's an option in the Tools menu to turn on the FPS counter - I average ~55FPS @ 1024*768
 
 
 
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SuperMicro P6DBS (dual UW-SCSI) BIOS 2.2, 2*Celery 300a @ 450Mhz, 384MB PC100 RAM
SCSI-A=4.3Gb+9Gb, SCSI-B=Tosh32x CD-ROM, Yamaha4416 CD-RW, Iomega ZIP100, IDE1=4.3Gb
IBM EtherJet 10/100 NIC PCI + Nortel ADSL "modem"
Matrox G400 DH 32Mb AGP + Quantum3D Voodoo2 SLI PCI (CL TNT1 AGP on a shelf)
SoundBlaster Live PCI (not Value)
Win2K build 2195 Retail (not 120-day eval)