demo vs game - performance collapses??

[cpickeri]

Hi,

I recently downloaded and played the penumbra demos on my PC running Ubuntu 11.04. The demos ran perfectly smooth with 0 performance issues. I bought the collection for $20 (great price) and now when I run the game it is unplayable. It could not be any slower....my mouse cannot even respond to my movement with the framerate I am getting. I have tried turning the graphics down and resolution down...not working.

Why would the demo run great and the game run so terribly?

My PC
graphics: ati radeon x850xt
mb = asus p5wd2
ram = 2gb
cpu = INTEL PENTIUM D 960 3.60GHZ/4M/800 LGA775 ES CPU (64bit)
and plenty of disk space