I just noticed my steam, and therefore the games it launched allways ran in vista86 compatibility mode, this seemed to be the default option, i never told steam or windows to do that. The usual way of deactivating it wouldnt work so i did this:
http://joshmccarty.com/2012/01/turn-off-compatibility-mode-for-steam/
afterwards i noticed a significant improvement in performance.
This could potentially be the cause of some crashes and performence issues people are expieriencing, so if youre having problems try this (allways be carefull tampering with the registry though) and post if it worked.