On the other hand, I have a more powerful machine (GTX590)but I haven't installed Steam on it.
I tested D:OS on a GTX590 which produced 40fps and a smooth paying experience. So the bottleneck seems to be the video card.
The strange thing is the low 20pfs performance on a GT630 on very low which probably means that the video engine is not optimized. You have to try the very low setting to see that there should be no high demand even for a modest video card. Very low should run on a laptop with integrated video, it looks that bad.
