LOUARDLEBARBARE: So, I bought Project Warlock a few months back. I launched it and played through the first level to see if everything worked fine, with apparently no issue. I had other games to play, so I uninstalled it to save hard drive space in the meantime.

I reinstalled it yesterday and started to play it, but the movement speed is somehow reaaally sluggish - both when walking and running. In the first level, First Steps, it takes a full minute to drag the character out of the starting cave!

I don't really see any reason to that, as the game otherwise runs smoothly. I also downloaded the "Arctic Attack" demo to check, and the movement speed there is normal.

Has anyone else encountered this problem? Is there a fix for it?

ArsGratiaArtis: Hi there,

Yes I had the same problem and was fixed by activating "beta channel" (in Manage installation->Configure->beta_portal).
This might make the loading screens longer (if you see a white screen when launching the game, just wait a bit before pressing any key).