Definitely not an exhaustive fix but did fix it for me on a Zotac ID80 with Nvidia GT 520m. Disable composite with
sudo nvidia-xconfig --no-composite
It’s a very obscure note on the XBMC’s unreachable wiki. It mentions that XBMC is not compatible with Compiz and has a link to a german site that among other things, has the code above. It works.