The only problems I get is the occasional missing texture, the mouse not working on the menu screen and
the space bar and 's' being interpretted as the same key, but I find that the Windows version has more glitches and crashes than the cider version. Perhaps it's down to the download, because I know there are different versions, some of which don't let you use the mouse or the spacebar at all in game. The one I downloaded was the distro marked "working perfect". I don't think I'm allowed to give any links, but I think we all know how to use Google!
If 25fps is the limited option, then I think I'm close to double that, which I think is quite an achievement on my spec. It's hard to measure these things though by eye - that's why I asked about a fps counter!