An example:
Zatoichi: The Fugitive
693MB, 1hour25minutes, 1 video track(DIVX), 1 audio track(vorb), 1 subtitle track, mkv created in mkvmerge.
Windows Vista inside vmware fusion 3, SP2, CCCP (filters used: haali, ffdshow video, directvobsub loaded), 1gb/s wired network (bridged mode in vmware options), MC in LS client mode (play local files option ticked)
Time to open the file: 50 seconds. (starts playing from 23 minutes into the movie because of bookmark). Try to seek to beginning of the file whilst it is opening and MC crashes. Opening it a second time after a successful opening the first time took 26 seconds.
Time to open the file with VLC on mac: Less than 1 second
Time to open with zoomplayer using MC's send to command: 25 seconds
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I tried random movies after that, some made in DVDFab, some in handbrake, and some that had been obtained by other means and converted using mkvmerge. All of them opened between 10 and 25 secs.