Welcome back. I'm glad to hear things are better for you now, TS3 issues notwithstanding. Having read some of your earlier posts, I seem to recall you're pretty well-versed this stuff, but I'll list the simple fixes first, just in case:
- Delete the 5 cache files in your game folder
- Clean game folder, copy the save over with no cc and only NRaas mods
- Rename the most recent backup save and load that instead
- Longer shot, but perhaps turning down your graphics options at the Main Menu, quitting, and relaunching would help
- Since you've probably had system updates in the last year, make sure your fps is still locked in at 60
- (Also maybe check RAM use on startup, just in case it's going way over for some reason)
- If none of this works, try a brand new game (save, quit, reload) to make sure it's not a global game issue
I'm sure there are more in-depth ways to troubleshoot, but that's a start. I hope something works.