Wow, really? I had no idea that was a feature built into the OS. TextMate certainly doesn't do anything like that, but it does preserve open windows and preserve the contents of unsaved documents between quitting and reopening. I thought that was all the new OS-level features did.
Delaying by 0.5 seconds doesn't really cover it for me. If I type half of a task and then need to go look something up before I can finish it, my script has already seen the half-baked task.
But I found the answer! You can turn off autosaving with:
defaults write com.hogbaysoftware.TaskPaper3.direct ApplePersistence -bool no