Player laggy when playing segmented mkvs

[DrEaMeR86]

Hi! I have a problem playing a mkv with ordered chapters/segmented link. The player plays the file and when it changes from the main video to the attached video the sound plays fine but the video becomes laggy, like if it is dropping a lot of frames. The workaround is to pause and replay (2 times space on MPC). WMP does not play the attached file, just black screen.

Any clue?