http://bugs.winehq.org/show_bug.cgi?id=23578
--- Comment #47 from Jeff Cook cookiecaper@gmail.com 2010-07-14 22:31:25 --- Created an attachment (id=29611) --> (http://bugs.winehq.org/attachment.cgi?id=29611) oprofile log - first 40 lines uncut
You're correct that kernel functions are the next highest on the profile. I've attached the first 40 lines in the log uncut to demonstrate this. Hopefully this is useful.
It does seem like this is a change that affects all Steam games, so something like Steam DRM/VAC is probably a good hunch.