This looks more like input optimization (macros, scroll binding, high polling rate) rather than just raw APM. Small hardware tweaks can make a big difference in micro, especially in RTS gameplay.  

Good catch, I'm suprised you could notice it from replay at x2 speed. I took the video while developing and there was a math flaw at the time. The formula I went for in the end is simpler using root degrees to also avoid any asymptote, which make it very safe if you input low values. Again, check https://gitea.wildfiregames.com/0ad/0ad/pulls/8892 if you want to go into details. The new capture regeneration system reward garrisoning stronger units. Would be a shame to remove it now with this. Also still don't think putting a hard cap is any good compared to diminishing return.

The rate cap I propose should be after accounting for regeneration, if that's possible. The only effect should be to stop captures faster than a certain minimum time (given, of course, by the total capture points divided by this effective rate cap).   But in your video it is visible, and it should be, that's the point. It goes from 4000 to 2000 points between 0:13 and 0:25, average of 167 points per sec, and then from 2000 to 400 between that and 0:39, average of 114 points per sec, which is 32% slower, and could be frustrating when one had an early estimation on how much it would take.

I don't like it that much either, but given that we do want to nerf specifically the faster captures, maybe this could be the lesser of evils. Somewhat, we cannot fix it with current balancing tool without impacting the normal capture, so maybe introducing a new one is necessary. I've set rather safe values for the PR, that should have noticeable impact only for the worse cases.

I was referring to the fortress. I agree that more points would be good. On the last point, I don't recommend adding an additional point of complication to a mechanic that is already complicated, as you mention in your OP. I agree with the other stuff, especially the need to nerf the high volume capturing scenario and not the small volume. To clear up some confusion about the nerfs that I introduced ahead of R28: by increasing the default regen rate, we essentially increase the number of units needed to achieve the "high volume" capturing scenario. At the same time, you are punished less for having an empty CC, giving you time to garrison it. I don't say that its perfect, but its better now, and in my games I see people go for siege more often.