Fallout4 significantly slower with BethINI

[SteppedOn]

TLDR; What BethINI file setting could be causing FPS to decrease by 50% during FO4 gameplay?

I've been going nuts trying to figure out why I initially start a session at 135fps and over the course of 3-4 minutes of just running a lap or two around Sanctuary I drop down below 70fps. This occurs even though my CPU (Ryzen 3400G) loafs along at 30-50% and my GPU (RX 6600) is likewise loafing at 40-65%. I do have 50-some mods loaded and I thought maybe it was High FPS Physics or ELFX that was killing me even though I added the PRP fix. However, read on and see why I don't think this is ultimately a mod issue.

I did tons of research and found lots of outdated posts that agreed on a few things & disagreed on a few others. (FYI: I'm Vsync=off, iPresentInterval=0, FreeSync=On) Yesterday, I accidentally launched FO4 directly from F4SE without pre-launching Steam (long story, but playing SSE taught me to pre-launch Steam). Suddenly I saw the original launch menu again with the Options selection rather than just going straight into the game. Huh? I played a bit and noticed that I was running a consistent 125fps +/-15fps! I looked more closely on the next launch & it appeared that a different INI file was being used as the settings looked more like MED while BethINI had been using the HIGH preset. I ran 4 initial test scenarios:

Launch Steam, then F4SE from Vortex dashboard (135fps & 50% FPS drop over 3-4min)

Launch Steam, then F4SE.exe directly (120fps 40% FPS drop over 3-4min)

Launch F4SE from Vortex & let it auto-launch Steam (125fps +/-15fps)

Launch F4SE.exe & let it auto-launch Steam (125fps +/-15fps)

Next, I went back and reduced BethINI down to MED presets. Same basic results. I let F4SE launch Steam and configured the HIGH preset with the same relative results. I did some digging and found that there's a set of FO4 INI files under {userdata - Steam is installed on C:} that is read by FO4 when F4SE launches before Steam and another set under {games - Steam library is on G:} that is read by F04 when F4SE launches after Steam. With both sets of files configured in their respective applications to use the HIGH preset, I still saw this significant difference in FPS degradation. I used WinMerge to determine there was about 20% difference in the Fallout4.ini files between those locations and even larger differences in Fallout4custom.ini and Fallout4prefs.ini. Is it possible that BethINI adding redundant entries across its 3 INI files that may be conflicting with each other? I really value the visibility and control of using the tool, but I just can't handle the performance degradation that comes with it. 

SteamFallout4.7z BethINIFallout 4.7z

[DoubleYou]

It sounds like you have performance problems when F4SE is not loading due to incorrect launch methods. If you fail to have Steam open prior to launching F4SE, it will fail to use F4SE. This is not INI related, but rather, an issue with an installed mod that uses F4SE. You can verify that F4SE is active upon launch by going to Settings menu. If will not display the F4SE version if F4SE failed to load.

Below is a picture showing the where the F4SE info is written.

[SteppedOn]

Actually, it was the opposite scenario. When I launched "correctly" by opening Steam, then launching F4SE and allowing it to start F04 is when I experienced the 50% FPS bleed down over time. When I launched "incorrectly" by opening F4SE and letting it open Steam, then open F04, I had great performance. However, I eventually realized that in the latter scenario that MCM was not loading, which made me suspect most mods were not loading either. 

On further scrutiny, I did find one corrupted line in the Fallout4.ini file that I corrected during my WinMerge session as well as reordering the entries to be consistent and more legible across all 3 files. I went back and did some slight optimization on Shadow, Grass and LOD settings per long-time user posts and made a couple of minor tweaks to High FPS Physics ini file as well. Somewhere across those changes a miracle occurred. Now, I can launch Steam>F4SE>FO4 and achieve relatively stably 120fps with my 60 or so basic mods active. I'm going to bow to the mod gods and chalk this up to some form of user error (but keep a gold copy of the working INI files!-)