VLC playback is choppy?

freakin' hate every single media player on earth now, first my WMP is messed up, now freakin' VLC... i use VLC to play mkv files right... today i go to play one on VLC and now the video playback is choppy but the sound still plays normally... media players have got so frustrated now, i can't watch videos or play music on my computer now... HOW THE HECK DO YOU FIX THIS STUPID VIDEO CHOPPINESS ON VLC!