Critical Description
HBASE--11135 changed append to wait on the update of the edit/sequence id. This slows writes by a significant amount (50% slower?). jeffreyz is going to look at updating MVCC inside in the ring buffer consumer thread just after the region edit/sequence id update. If that works, then we can undo having append wait on the sequence id update and get some of our speedup back. Marking this 0.99 and blocker so we don't forget about it (Undoing the wait is just a case of removing the few lines of latch code in FSWALEdit).