I run a full modded game, with most SS2 add-ons installed. Exceptions are RotC and the large junk fence addon. At first after leaving the Vault I talk with Cods, follow him around shoot some things, then I put my scrap bot at work, while it is scrapping the Settlement I visit the museum grab the 5 and return to Sanctuary, I then pick up the magazine, build the beacon and meet the awesome Stranger. I lay the plot down, he shoots off, I visit him, we return. Till that point not a single save issue. Every time within a second I have a new save.Another thing I was thinking was... has anyone tried playing a modded game that has SS2, WSFW and SS2 - Chapter 2 installed, but without actually doing any of the quests, using the holotape or anything else to 'start' the SS2, quest lines etc.,.? Just to see if the problem rears itself with just the inclusion of the data files (which it shouldn't) and other mods. Then after a certain amount of time, start the main quest but don't build anything. Play for a bit, testing the save times, then build the first residential plot. Play for a bit... save some... to try and see at what point it seems to appear?
From what I've read, it seems to happen after industrial plots, which I'm using RoTC and it doesn't happen all the time, it's very random but I'm thinking it didn't start until I fired off SS2 using RoTC (not implying the problem is with RoTC, it just uses SS2 functions). Here's a sampling where each time SS2 was started without using (or necessarily picking up) the holotape and just from the MCM settings:
watching for un-responsive task: 'Fallout4(24136)'.
'Fallout4(24136)' was un-responsive for '5' seconds.
'Fallout4(24136)' was un-responsive for '4' seconds.
'Fallout4(24136)' was un-responsive for '48' seconds.
killing un-responsive task: 'Fallout4(24136)'.
watching for un-responsive task: 'Fallout4(21604)'.
'Fallout4(21604)' was un-responsive for '1' seconds.
'Fallout4(21604)' was un-responsive for '15' seconds.
'Fallout4(21604)' was un-responsive for '11' seconds.
killing un-responsive task: 'Fallout4(21604)'.
watching for un-responsive task: 'Fallout4(16604)'.
'Fallout4(16604)' was un-responsive for '1' seconds.
'Fallout4(16604)' was un-responsive for '4' seconds.
'Fallout4(16604)' was un-responsive for '10' seconds.
'Fallout4(16604)' was un-responsive for '160' seconds.
'Fallout4(16604)' was un-responsive for '60' seconds.
end task resource monitoring: 'Fallout4(22096)'. <--- normal quit game.
This is from 3 gaming sessions (sorry about the time stamps, I'll code that in here in just a sec). When the 'Fallout4.exe" was auto-killed it was because it was waiting over a set tolerance (60 seconds). I've upped to 180secs, or 3mins, to see if most saves fall within that range. Interestingly, the time the game is un-responsive goes up, then middles out (without further sampling I can't tell it it will go up again and always middle out).
Normally the snapshot only takes a second most of the time, it's a moderately modded game, with at least 5 settlements somehwere in the RoTC building it all framework (though realistic build times is ON).
Quick Edit Note: All the 'un-responsives' were detected when trying to save the game.
The save game bug kicks in after laying the first plots, when you've met Paul and Lilly.
Like your figures shows when SS2 starts doing it's things it's consuming process power.
When you manual save at that point the freeze happens since the game and SS2 both want to dump their records in the save file, the result is something like a buffer overflow.
When you compare the actual size of save files pre chapter 2 and now, there is also a notable difference. After 3 days IRL 8+ hours play time with chapter 1 I reached with save220 a file size of 47.626kb. at save 16 it was 23.613kb With chapter 2 installed I'm at 31.428kb and not even close to save nr 16.
When I go to Tenpines for the first time (when the save is done) I can run and press the manual save and have instant saving back.
This behaviour repeats itself everytime when you are near a settlement with plots or just have placed plots. It's confirmd by several users, all who have exactly the same mod setup as I have. Maybe this is usefull info.