The alpha version is not optimized for performance, so the game is currently indeed a lot more resource hungry than it could/should be, as you obviously have noticed.
In the words of
Donald Knuth. "Premature optimization is the root of all evil (or at least most of it) in programming."
I hear that (completely) enabling/disabling shadows can result a disproportional effect on performance. Last time I checked, disabling had to be done by manually editing the config file in D:OS's folder "my documents". Maybe it would be interesting if you could see how performance scales on your system by using different settings.
On my system at home, I get a good 40 fps (according to fraps) most of the time with ultra settings on 1280x1024 (yeah yeah I still have one of those
). It is a core 2 duo 3GHz, with 4GiB RAM and an AMD HD6850.
Also see this
somewhat related older thread.
)
