Having some trouble with low fps for this game. Won't go over 20 fps. Any ideas?

No.

It might come in handy you post some of your system specs and what detailsettings you're using.

I have a Intel i5 4690k
nvidia Gtx970
16gb of ram.
and I have the game installed on a SSD

In the game select HAL T&L and choose highest detailsettings not auto.

Me too.

Had same problem with new(-ish) 4-core Xeon and new nVidia 1060/6GB. Game was very sluggish at 1920*1200*32bit, 20-50 fps. Problem is entirely game's strange rendering-engine, you HAVE TO choose "Direct3D HAL" instead of "Direct3D T&L HAL" in game's Video Options -> Interface. I suspect that game don't like newer nVidia drivers or something? But after non-T&L -selection I successfully pumped up all nVidia Control Panel -settings and got stable 60fps. Stability was not an issue, not a single crash or anything like that, just poor frame rates considering hardware. Game is so old that it should run maybe 500fps with gtx1060...

It's been like this since forever, even on Geforce 2s back in the days it ran better without T&L :)