[Toadling]

OK, now I see what you mean. I tried it on several very large emails in Mail and the Clip-O-Tron does seem to take up to 10-15 seconds for very long emails (i.e. not large attachments, but very long email bodies with lots of embedded email addresses).

Note that I do not see this delay for medium to small emails though. Still, I'll open a bug report with Omni Group so they're at least aware of the issue. You might want to do the same (Help -> Send Feedback in OmniFocus).