Looking at foldit threads I observed something odd: there are 2 dsound.dll process that are working and making few % of cpu usage. Odd thing is, that I have all sound/music disabled.
Second thing: there are in log.txt file "playing sound" commands - again, all sounds muted.
There is also winmm.dll!EnPeriod process that is related to sounds.

Funny thing is, that I can suspend those 2 threads and client is running w/o problems ;]