Going from 11.0.6300 to 12.1, one thing is certain. Auto-protect for Microsoft Outlook is much slower. We are running Office 2010, fully patched, tied to Exchange 2010, using SSL.
Opening a TIF or PDF can take up to 10 seconds. Subsequent opens of the same file are instant. We have users that all they do all day long is open bills in TIF or PDF format. So adding 5-10 seconds per attachment is not acceptable.
For the time being I have removed TIF and PDF from the file types we are scanning using Outlook Auto-Protect. Hopefully a better resolution will be in 12.2.