Finally I have find some time to make video... when HUD is disabled video runs good, but when it is ON you can see tearing. Video file is 2560x1080@50FPS in ProRes422 (I know that it is VERY HEAVY), I used this file because it describes this problem best, but the same thing I can see on SD videos when using TripleHead, Graphics Load indicator is not overloaded, but performance is pure... When I boot 10.6.8 (second HDD partition on this Mac) everything runs perfect, and no matter is HUD is on or TripleHead is used...
link for video: http://www.ex.ua/75535915 (now it is locked and no one can delete it, because previous 2 files were removed by someone unknown )
and system profile (ZIP, because it is too big for upload it to forum as is):
