Weird thing is first thing I tried after the update and after restarting with my “UK mods” profile enabled was the new Landing Challenge and that bombed.
That’s neither in the UK or using a 3rd party plane (Cessna 172 which I have no mods or skins for I think) so that threw me. I assumed it was a utility so I disabled everything and the Challenge then worked. Then I enabled Utilities only and it still worked. Baffling.
I currently have 1340+ addons in my community folder. Mostly payware. Recently removed all the liveries since some caused problems.
No noticable hit on the FPS. (my FPS depends on the mood of the sim anyway 
)
But long loading times and since SU9 I have the problem that something is in the folder is causing ctd’s, so I will spend my night searching…again 
A kingdom for a log file 
Ran out of time to get to the bottom of it again. So far:
799 = ok
818 = ok
822 = crash
825 = crash
833 = crash
893 = crash
894 = crash
It’s very weird though. Yesterday it was crashing when I “only” had about 260 enabled - and now the same plane (Stearman) and same area (different airport but close) works with 818. I don’t get it. There is something screwy and more to it than I have been able to understand for certain yet. Might still be a single addon somewhere in my case. Maybe it’s a plane even if I’m not flying that one? Maybe it’s a livery? I’ve run out of time again to find the exact number of items (between 818 - 822) it crashes on or if it’s something else, so will resume the fun tomorrow!!
It does point towards having less loaded is more stable now though.
I still haven’t decided exactly how I’m going to make life easier for myself. Tried using the Dependencies links in the app but I’m not fully understanding something about how that works.
Big problem is all the shared assets / libraries. Not sure now what was required for what airport (I’d need to go right through my FS.to history and check every one!?) so I just load them all but that is 270+ items on its own. Wish the creators would bundle them up into a single asset, but I see why they don’t.
On the plus side, loading to the main menu does seem quite a bit faster now.
EDIT: By the way, total GB size on my list was between about 290gb to 360gb so nowhere near your terabyte, so doesn’t look like it’s size-related issue.
Thanks! Your findings at least help us confirm it’s not a specific GB size or addon count, like you said - something screwy happening here.
I remember on prior builds I had a similar issue where at a certain “tipping” point my content manager wouldn’t load, seems like that bug may have evolved to causing CTDs now.
Tonight I got a CTD with ~600 loading so that’s put a spanner in the works. Elimination time again … 
Right, so after much digging, enabling, disabling and rebooting I finally found the CTD culprit (hope it’s the only one)!
It was the Touching Cloud FA-18e-sw mod.
Ran out of time (again) and want to have a little fly now before bed! Will try over weekend to see what number of mods I can actually load now that I know not to include the F18!! 
EDIT: I wasn’t ever trying to USE the F18!
That’s good to know, that is one of the mods I have loaded as well.
After more testing seems the problem was ONLY that F18 so far!
Managed to load flight with 893, 895 and now back to my main worldwide set of 1082 with no crssh.
Of course I cannot rule out every airport and item (if it has problem when I get near) but seems fine!
Still the issue remains that Content Manager gets stuck loading the list with >1000 ish, but I can return to main menu after a flight now (which was a problem before).
Basically no 894 limit for me - I suspect one of the things you added was coincidentaly the fault?
EDIT: Spoke too soon, gets stuck returning to main menu
After removing the F18 and the Hueys I am again able to fly CTD free.
I had the CTD on return to main menu in the last build, it was a PITA.