720p XVID advance simple@L4 or L5 stuttering problems

Hi

While playing any XVID 720p coded with XVID advance simple@L4 or L5 often I got stuttering problems, using XBMC I got breaks for buffering. Bitrate is about 3k.

Playing movies with bitrate 4,5k coded with AVC there are zero problems. So is it hardware limit or not fully implemented XVID codecs?