I am sure there are more, the ones with question marks are unknowns but heard of in the ether somewhere. Any additions or confirmations?
I have the first phase of Frequent Update Optimizations (HOT) patch ready. But I held it back because of the concerns that its too complex. It has shown decent performance gains on pgbench and DBT2 tests though.
I am splitting the patch into smaller pieces for ease of review and would submit those soon for comments.