I can confirm that this has happened to me yesterday, after the latest update. I can also add that, if I start seeing the signs of the slowdown a bit early, and if I'm fast enough, I can save the game, and load it, and it will solve it for a while after. RAM usage doesn't seem to go through the roof (I have 32GB and the % used was not very high), but this behavior feels like there's a leak somewhere, and that would explain why you can load the same information/game, and things are fine again.

I did not check the GPU memory used though, but maybe there's a clue in that.

Also, CPU usage has been relatively low.

OK, here are some screenshots:

GPU usage, when the issue starts: https://prnt.sc/w6lnta

VRAM usage: https://prnt.sc/w6lpfl

Another point I'd like to add, is that it seems that it happens a lot faster, the more turns have been played, which makes me think it may be related to the number of units, or assets being loaded (population becomes a lot higher, the longer the game goes)

I would agree with that. Perfectly fine gameplay after reloading the app. I did also notice that my graphics and UI display size settings were changed after reloading. Though not sure if that's just from the base game, or having to force close it. 

Having the same issues. Turn 109, the game became unplayable, saved and loaded back up, and so far it's alright again. 

check your diags file.  there is likely an error being detected and abort taking place.  include the diags file per the bug description tutorial to help the devs nail it

Same here. Seems like my CPU is hitting 99 degrees Celsius on all cores when this happens. Not sure if a leak is causing the CPU to hit TjMAX or if the late game simply overloads the CPU. Exiting to desktop and restarting the game after CPU cooldown solves the issue for me for about 20-25 turns. 

I had an issue where it appeared the G2G servers went down around 2am CST and that caused the game to freeze up...and since I had stepped away, I didn't get a save in (and apparently lost 15 or more turns).

I'll have to try again (I started a fresh game today to try a few other things out) and see if I run into issues as I get further into the 100+ turns.  I will also try to watch my memory etc.  I have an older Ryzen 5 1600 1st gen and 16GB of 3200 memory.  Video card is not an issue...RTX 2070 Super.