In T325087#8465636, @Tgr wrote:

Not related to the task but getEffectiveMentorForUser() is called something like 10 times to display the homepage (mostly because it is invoked by canRender() which is used quite a bit). It should really have an in-process cache.

MentorStatusManager is fairly expensive (it checks for (b)locks), and called a lot (on every pageview, due to Help panel). Add an in-process cache to it, and possibly a WAN cache as well, to avoid submitting too many queries.

QA notes

This task should not cause any differences in Mentor dashboard's behavior. If the caching logic is broken, it can cause Regression about mentor's status change not applying properly (still being asked questions after setting their status to away and similar).