We've witnessed the jerky 3ivx playback but weren't aware it affects Podner's output. We've got files here that play terribly but when Podner is done with them the results are fine. Can you confirm Podner's output is as jerky as when QuickTime Player plays your files? If so, we would really appreciate a chance to look at one of your files so we can try to determine why this is happening. We would certainly contact the 3ivx guys and make them aware of the issue.
While DivX 5.2.1 is not compatible with Tiger, we have had good results in testing the latest beta of DivX Fusion for Mac, available at
http://download.divx.com/labs/DivXFusionBeta3.dmg .