I have a 3hr 50min, 1280x720 Apple ProRes 422 file, (100Gb) that I imported to Motion 4.03 and just added an animated Date and Time Line, broken in 4 different segments. I have a MacPro 2,1 with Dual 3GHz Quad Cores and 20GB Ram, 300GB Raptor boot/app drive and 10TB Raid. My export time using native output, no additional compression, just dropping audio to mono from stereo, has been over 6 hours. When theExport box shows a complete progress bar, it says 'Time Remaining: Unknown. If I stop it, I have an un openable .mov file. If I leave it running, the output file continues to get larger by 50MB/min.
Activity monitor shows 1 core of 8 maxing out intermittently, I checked the Batch monitor and it showed a job with the same lapsed time with an additional 41 Hours remaining!