I’ve test-upgraded my most used wiki.
The upgrade of single file wikis seems slightly slower than it used to be; now it takes noticeable couple of seconds to finish, whereas for the older versions (tested it v5.3.6 > v5.3.8 right now) it was almost instantaneous. Not a problem for me at this scale, but I wanted to point it out just in case this is a sign of some inefficiencies that could make problems with bigger wikis.