Ok. After more testing, I think it's safe to say that the problem is SOLVED. So here is the conclusion:
-My GPU was overheated, to the point it exceeded the temperature limit, which is 83 C by default, so it throttle itself to remain under the heat limit after 15 minutes of gameplay. This is dueled to the fact that my GPU fans wasn't performed at full potential.
-Download MSI Afterburner, set the fan speed curve to a more aggressive percentage (100% at 70 C), and the GPU no longer throttle. Solid 60 fps during my 2 hours of testing.
I post this here so if anyone's having the same issue, here is a throughout solution. Kudo to the Nexus member AtomicFallout757 of the Buffout 4 community, who pointed out the GPU heat issue right away, just by seeing my before and during pictures of the lag. Seriously, thank you kind sir. You are the light in the deepest dark for me and so many people. I can't thank you enough. And that's it. See you guys out there in the waste, fellow wanderers.
My game start out real smooth (solid 60 fps in my settlement Sanctuary), then becomes very laggy after 10 to 15 minutes of playing (30 fps in the same location). I think I have a memory leak, which is a totally new concept to me. My game is modded (218 plugins total, more info below), and I have some modding knowledges, specifically: load order, BethINI tweaking, using the mod Buffout 4, and FO4Edit. I have basic knowledge about PC (been using it my whole life), and unfortunately: zero about codding, computer mechanics,... You know, the good stuff, so i have no clue how to fix this or even where to start. Any help will be tremendously appreciated, and I mean ANY. Point me to a direction and I'll chase it, whatever it cost. I love this game too much, and I can't live without it (long story short: it's basically my life), or at least not having to play for 15 minutes, save, quit the game, then load it up again. If I have a code for this situation, it will be code RED, since it freak me the F out rn.
Anyway, enough of me whining, here is some more infos for you guys who want to help:
-My mod manager is Vortex.
-My Plugins and Load Order:
-From my knowledge, the papyrus log files can be quite useful in some situations, so here is my Papyrus.0.log file:
-Some of the methods I tried and failed to fix the problem:
[2021 Tips] How to Fix Fallout 4 Lag Issue
-My crash log greated by the mod Buffout 4, using the "ctd" (crash to desktop) command from the mod Console Commands Extender, at the moment that my game was lagging:
That's the end of my knowledge. Seriously, from the bottom of my heart, thank you for your time. I will proceed to find the answer while waiting patiently for your comments.
Edited by haitan95, 10 June 2021 - 11:32 PM.