Is /config/cache/ showing significant cache fullness?

I turned on XHPROF sampling and grabbed some data:

I took a screencast watching htop over a ~1 minute period (filtered to show only PHP processes). It looks like /conpherence/panel/ and /notification/panel/ are quite CPU intensive.

Or, more specifically:

Oh, it doesn't actually create any peril until we try to use images larger than 50x50px (I was confusing it with some other unrelated issues), but I think it's still better to fix it now. It looks like using 100% works fine.

D12821 creates a bit of a problem: the CSS will expect 100x100 images, but all old profile images will be 50x50.

Also:

I'm going to tackle profile pictures first. I think it makes sense to denormalize them onto PhabricatorUser, not do them as a separate cache hit, because we almost always need them and they're very easy to dirty. We have some related technical debt which I'm going to try to clear first:

Quite possibly we should just denormalize profileImageURI and calendarStatus + calendarStatusTTL onto PhabricatorUser, since we almost always need those anyway and mixing real object queries with a read-through cache isn't a great v0 feature.