Welcome to the fastest version of Review Board yet.
1.6.10 is chock full of performance enhancements. It's lighter on your web servers and on your database and noticeably faster. Review requests load almost instantly and the diff viewer renders diffs faster.
You know those "X minutes ago" timestamps? They weren't very cache-friendly, and required a reload to update. Now they're live, even when viewing a cached page. The timestamps everywhere in the UI will update as time ticks away.
There are also some fixes for diffs with very long lines (generally for datasets or minified files), fixes for Mercurial repositories, and fixes for excessive update checks on a review request.
There was a lot of internal work done for these optimizations. We have been dogfooding this pretty heavily, but please let us know if you find any regressions.
Full release notes are available.