Ahh thanks for the link. I vaguely remembered reading some posts about optimisation over and the above the general behaviour I mentioned (probably including the post that you linked, but I vaguely remember other posts as well), but I couldn't remember whether those posts were talking about 0.16 or 0.17, or even just possible future optimisations, nor exactly what the details were. Still, to me the Gifs still resemble the behaviour I described. (But more analysis on one of those GIFs below).
If I have understood Posila's post correctly then the personal roboport area is divided into 49 subzones, and the personal roboport checks one tile from subzone per tick. (It is definitely possible that I'm misunderstanding Posila though, and the personal roboport area is divided into multiple subzones of 49 tiles each. The wording doesn't seem to be very clear to me). 12 vanilla Mk2 personal roboports have a range of about 139 x 139, and cover about 19300 tiles. So even checking 49 tiles per tick, it will still take 394 ticks (13 seconds at 30 UPS) to cover them all. (I'm not sure what the actual range of those 12 Angels + Bobs roboports are, but from https://gfycat.com/barreninnocentcurlew, a construction area of 139x139 seems a reasonable estimate). Even if I have misunderstood Posila, then the those 7x7 subzones will still need 49 ticks to check, which is around 2 seconds at 20 - 27 UPS.
Looking closer at https://gfycat.com/barreninnocentcurlew. The blueprint is placed at about 6.15 sec, and I'm guessing that the section that is inside the personal roboport range has around 300 items, (plus some rocks and trees for deconstruction). By 6.22 seconds there is a swarm of construction bots flying (some of those are dispatched to deconstruct items), and performance is down to 20 UPS. It looks like the last construction bot for those 300 items is dispatched around 10.4 seconds, at which point performance is back to 27 UPS. So in 4.25 sec (roughly 100 ticks at an average of about 24 UPS) the game dispatches around 300 robots for an average of about 3 robots dispatched per tick. (Also note that Neferous only has 300 bots, so it is possible that the game dispatches all of them, and needs to wait for some to return). That is way better performance than I estimated. Also note that it would be less than 2 seconds at 60 ups, which doesn't seem like a problem.
For reference Neferous's configuration
