The new VLC has better optimization, everything runs smoother. It shows even more when you're trying to play mkv files. On the same computer, 480p mkvs lag under the old VLC and play smoothly under the latest one (I used to have a minimal Leopard install). For HD 720p the difference is even greater : the old VLC can't handle it at all (HUGE lag) while the newest plays many files smoothly (not as good as CorePlayer but I sometimes need subtitles support).