Just for the sake of testing:
Remove the npcs entirely. Double/Triple all health and timers on objectives. Require more than 1 person to be standing on a flag.
Just do it for a day or two (maybe a weekend) on the live servers with actual population and see how performance is. Pre Plan, post about it so people know ahead of time, give some incentive for showing up to the test. (Maybe MYM style)
Look for the following;
Dips or improvement in performance - especially in keep battles
Positional desyncs - Why does it seem like the game struggles more with NPCs not being wonky than anything once a surplus of players are around?
"Everlasting Status effects" and bugs. - Will they still exist? Will we still see 4 instances of 10,000 days of burning? - I've got a theory on this one after some testing this weekend on Xbox