I've been doing a bit of optimizing today.
Retired the Sponsored with Love feature to save a few template queries.
Removed sorting on VA listings on character profiles to avoid temporary tables.
Currently looking at query cache usage. With a large cache, any change that involved invalidating 100,000+ cached queries caused a bit of a bottleneck. With no cache, page load times soared along with CPU usage. Testing out a leaner cache at the moment.
Added a link to the
old visual search to the front page. With it, you can set the search criteria first, then request results. Ends up a lot less load on the server compared to the
current visual search which requests results on each trait selection.
Also stopped recording gender ratios on each source.php page load.
The fewer UPDATE / INSERT queries the better.
Switched to a lazy update system for member accounts. Will only update last seen once per day, once per hour.
Add a Character 
A-Z Characters
Top 5 by Year
Latest
Tags
Lists
A-Z Series
Calendar
Who
News