Before using kdenlive I have been using Sony Vegas Movie Studio on Windows. Kdenlive seems to render DV to MPEG-2 clips about 2.5-3x faster than Sony using similar parameters. I can play the kdenlive files on Sony, and Sony reports the parameters of kdenlive renders as being the same as the Sony renders, so why the big difference in render time? I'm running on a dual core machine and as far as I can tell the Sony setup allows it to have up to 4 simultaneous threads during rendering. I think both programs are using both cores, but haven't looked at CPU usage figures while running yet.

Ah, just had an idea, could my AV running on Windoze have that noticable an effect? I wouldn't think so, but I'll try again with it shut down and see if anything changes. In the meantime any comments would be appreciated.

Turned off NAV and performance was about the same, not surprised.

Then looked at CPU usage during rendering, 100% with kdenlive, ~30% with Sony on windows. Noticed page faults and page file size were both pretty high. I had increased a setting called "Dynamic RAM preview max" from 128M to the max available of 1024M, which seemed reasonable given a 2GB RAM machine. Apparently that was causing the page faults, setting it back to 128M increased the rendering speed to where now the Sony is 2x the speed of kdenlive.