Can somebody explain to me why when I put two video files in two video tracks (on top of each other) ie. mxf file on top track and m2ts file beneeth, and I hit "enter" to preview it my mxf file plays 7-10 fps although it should play in real time BUT when I disable the bottom video track with m2ts file it immediately starts playing the top file in real time. Why Vegas 9 doesn't IGNORE the bottom video track???
(no filters etc. just two plain video files)

Why should it ignore the second track? You could be doing a key or something. If you mute the second track, does it play at real time? I don't understand why you'd want this automatic ignore a lower track. Seems like a real pandora's box.

If the track opacity is set to 100% and there are no filters appied it should ignore the lower track.

Marius is right. If there are no alterations to the top video, AND the compositive settings haven't changed in the track's settings, then it should play in real time.

However, if you don't put the M2t file below it, does the MXF play real time? If yes, then that is a real bug, and you need to report it to Sony. If no, then Vegas is just not fully optimized for the internal format of that MXF file.

Another thing to try, make sure your MXF properties dialog doesn't have transparency set (alpha).

Marius,

Your right, I've noticed the same thing and I'm pretty sure it did not do this in 8.0. One other thing I've noticed is that if I want to export a straight Cineform file (no effects applied) I have to solo the Cineform track or it will have to render the whole file (very slow). If I solo the track "no compression required" is displayed in the preview window and it's much much faster to export to Cineform.