The stuff you've seen on the boards is most of it. I've also chased slow "acs_object_party_object_map" queries and have replaced most of them with "all_object_party_object_map" queries. Postgres is universally faster with the latter view, Oracle seems to at least almost, and maybe always, faster with it.
You probably won't have those because the code's littered with them, unlike the LAUSD (Jon Griffen et al) change to permission_p() which was a one-place drop-in improvement.
I think the major thing we did was to move posting stuff from acs-messaging to acs-mail, and the API should be the same but with a different package name. We did that because we needed to rip out dependence on Oracle's Java SMTP (which Postgres doesn't have) and wanted all SMTP stuff in one place.
There's a minor change to the workflow API, too, involving notification callbacks but I doubt many people are impacted with that because I get the impression that not many people have worked with workflow (they should, though, especially as it improves!)
