I may have figured out at least one reason why #Friendica always seems so slow.

The memory limit of PHP is low, and has some(?) external variable in conf.d/friendica.ini that overrides the setting in php.ini. Before this, my deferred workers list was up to 999 (even before re-setting up the cron job). According to the table it was in reality over 4,400. Now, after increasing the limit in both ini files (and just straight up wiping the workersqueue table after), it's back down to 68, and the server runs faster than it ever did. I think workers get deferred over and over for external reasons, and eventually these build up past the point that the worker can handle it, because of the memory limit, bogging down the server.