- CACHE_TEMPORARY is gone. For sites that do not have content updates more frequently than cron runs, they should see much, much better cache hit rates.
- minimum cache lifetime is also gone. If you have frequent content updates, and previously had a long minimum cache lifetime set, then you'll see worse performance here, since there's no longer an attempt in core to rate-limit the cache flushes. However you also skip an expensive variable_set() every time a comment or node is updated.
THIS CHANGE RECORD NEEDS TO BE REVISED It links to the same issues as [#1534648]. Its title is nearly identical, yet the contents are vastly different. They probably should be merged.
The other entry is better; marking this one as abandoned.