Extra "dead" time when exporting parts as WAV files

When exporting individual parts as WAV files, I can monitor the progress of the export not only using the progress bar of export dialog, but also in the mixer - the volume bars move up and down as if the piece is playing. But after the progress bar gets a little past 50%, the volume bars in the mixer stop moving (suggesting that the piece is over), but the export still has not completed. Has anyone else observed this? Wondering if this is a bug in the code, and if total time for export could be shortened if this is cleaned up.