QuickTime decoder no longer default
In version 3.5.x, as default, QuickTime was used. QuickTime runs much better than the hardware decoder during my experience; from downloaded content to streaming content. Please change this back or at least make QuickTime an option in settings/video/decoders
Hardware decoder is noticeably worse with the mini player. Try adjusting the size and you'll see greater lag with hardware and software than QuickTime.