By so slow I meant that interactivity was not possible, I turned the view of the character and seconds later the character performed the action. In addition to that, the textures didn't display correctly, sometimes there was some kind of changing colors on them, maybe I'll try to reinstall the game. I am going to ask in the Frictional Games Penumbra forums about the GLSL, OpenGL requirements of Penumbra.
I just updated to mesa 7.7.10 which updated also libdrm... I'll let you know the results.