uGrids 5 = 5x5 cells = 25 cells loaded into memory.
uGrids 7 = 7x7 cells = 49 cells loaded into memory.
uGrids 9 = 9x9 cells = 81 cells loaded into memory.
And so on. This will lead to events being loaded far before the game intends for them to be. Script overload in Papyrus will be insane, and we see examples every day of people complaining about it,
yet those of us who stick to 5x5 don't run into those problems and thus can't reproduce them thus leading to anger and hate.
I get that you want some kind of scientific answer to this, but there isn't one. This is quite literally a textbook example of "DUH!".
Until this memory patch allowed people do to terribly stupid things to their games, most folks only dared to push things to 7x7 and didn't experience as much trouble.
Occasional reports of broken quests, events not concluding properly (or at all) and various other things relating to script overload.
Not to mention increasing reports from people about simple AI "standing around doing nothing" just like what would happen to you in the older games.
Just look at all of the script lag reports. Broken quest reports. Broken AI reports. Broken event reports. Crashes from spawn overload. You name it.
You can mess with the Papyrus settings in the ini, but as SMKViper has told us numerous times (he developed the system) it isn't designed to be messed with.
Raising stack and allocation memory doesn't mean the script VM can actually handle it when you do that, which puts the uGrids fanatics into an unresolvable paradox.
Higher uGrids = more scripts to process -> give Papyrus more memory = VM can't handle it thus generating lag -> crashes and broken [censored].
As I've said several times, there's more to the uGrids than JUST the visuals. Pretending these things don't happen and then trying to convince the public that there's nothing wrong with it at all is a huge disservice to everyone.
Especially when time has to be taken to set people straight on something that ought to be extremely obvious with 5 minutes of critical thought.
The nature of gaming and modding means the examples and data you seek won't be neatly presented in one place. It's more of a collective conscience at this point.