Today I released an update to the Navigation Bar - well, actually to the underlying database indexes.
I noticed, thanks to Yetzirah's diary, that diaries with lots of entries took a long time to load after installing the navigation bar. It took most of the day but I tracked it down to the database. After further investigating, I discovered it needed some additional indexes specifically designed to speed up the navbar.
I've now implemented it, and made a massive change to the way all the components of the system are stitched together to help further improve performance (not that it was much of a problem just now but if it ever gets busy around here again it will). I won't go into detail but it took a lot of work, but it's now completed, I think.
Anyway, queries for Yetzirah's Navigation Bar have improved from taking 3 seconds, to less than 20 milliseconds.