[IntlOrange]

That's pretty much it. It sometimes will take Mail.app over a minute to process the one "rule action" that moves an incoming email to OmniFocus. Is that normal?

I'm using 10.5.3 with Mail 3.3.

[JKT]

Try moving the rule to be first in the list in Mail's preferences. I don't know if this is still the case in Leopard but, iirc, Mail in prior versions of the OS performed rules in the order that they occur in your preference listing.

That might help to speed it up.

[IntlOrange]

Wow! Thanks, Jonathan. I tried that, and it is much, much faster now, taking only 3-4 seconds to process each incoming task. Thanks for the tip.

I still don't understand why it makes such a big difference, as I have only one other (very simple) rule in there, but I guess I don't need to know.