Framerate Issues Since Dawntrail Launch

[Cindertail]

Well, if the only bottleneck is the GPU, then pushing roughly 2M pixels(1080p) vs 1,4M(900p) should be noticeable.

Don't forget to update us, though. I'm curious if it's simply a case of slow hardware for the updated game or if it's also the game being weird as it is in my case.

So, here's an update of sorts. Bear with me, it's kind of complicated.

Reducing my game's resolution from 1920x1080 60hz to 1600x900 60hz sort of helps. I say that, as I had a bit of inconsistencies when it came to testing The Abyssal Fracture & Storm's Crown.

1st run of Abyssal Fracture - No noticeable slowness, ran perfectly fine albeit a bit dark (might just be a gamma issue).
2nd run of Abyssal Fracture - Lagged Slowness twice during Nostalgia's cast. Not the arms hitting the arena, but the roar SFXs.
3rd run of Abyssal Fracture - Slowness once during Nostalgia's cast.

1st run of Storm's Crown - Noticeable slowness just from beginning the Trial. Only got worse during the second phase.
2nd run of Storm's Crown - Only had one issue of slowness, and it was during the second phase hair tethers.
3rd run of Storm's Crown - No noticeable slowness.

I also ran the level 100 MSQ Trial, the name of which I won't share due to spoilers. I had no slowness, stuttering, lag or framerate issues.

This beyond baffles me. I had no issues running Endwalker Trials prior to the graphical update, and both Benchmark Tools scored Really High. Before Dawntrail (for a whole three years) I was accidentally using my integrated graphics instead of my Nvidia card to run the game, and played on a single display (the laptop itself). I had no issues running content back then. I started using my Nvidia card and a 24 inch, 1920 x 1080 native secondary display as my main monitor a couple days after Dawntrail released, as my irl PC-expert friends came by to try and take a look at my laptop when I started having problems running this game. I've seen significant improvement just from switching over my display alone, as before cutscenes and towns lagged horrendously for me, and the stuttering I received from Dawntrail dungeons decreased. The weird part is, before switching my resolution I would go hours without any lag in Dawntrail content, stuttering or slowness. However, I assumed it was because I would always play during off-hours for Primal. Not as many people on, not as much server load I'd assume. This was during early access, too. This slowness is far too inconsistent to really pin down what could be the problem, and it irritates me. My PC expert friends believe this could very well be an optimization issue with the game's engine, and part of me believes that could be the case. I just can't really fathom to imagine why my system can't run this game at mid-to-high settings. I'm tired, exhausted, and stressed beyond belief at this nearly two week-long endeavor of trying to find a solution for these boss-related particle effects that slow down my game. My cutscenes, my hub world, my login-screen can all handle High graphics with a solid 60 FPS, and so can content too - until I see these boss-related particle effects.

Here is a list of everything I've done:
Updated my drivers, made sure Windows 10 is up to date
Cleared my cache
Unscrewed the laptop and cleaned the fans and whatnot (friend did this day or two before Dawntrail)
Switched to full screen
Got a new second display (the 24 inch display)
Messed with Nvidia Control Panel for both my new display, the game, and my graphics card
Used RivaTuner for FPS capping
Disabled Microsoft Device Association Root Enumarator & Microsoft RRAS Root Enumerator
My laptop doesn't have the ability to turn DLSS on/off or use PhysX.
The only things I haven't tried are repairing the install, uninstalling/reinstalling, or rolling back my Nvidia Driver update. Not that I think any of this would work, but you never know?
My laptop's a cool temperature, it doesn't exceed in GPU or CPU usage when running FFXIV ever since I moved the game to an SSD prior to Dawntrail. Every other aspect of this game is perfectly fine. 3 second load times, textures, lighting & shadows don't chug my game in the overworld or even dungeons. It's just these boss-related particle effects that's proving to be a problem, but like I said it's inconsistent. I'll go hours without any problems, then it will just happen.

I just don't really know what to do at this point. I doubt Square Enix will come out with an announcement and somehow fix the game's optimization for everyone. This frustrates me to no end, as I can't afford a new PC and I just want to enjoy this expansion without these problems.

Edit: I play with teammate effects turned off/simple. Thought I'd mention that.
Edit 2: I tried what you mentioned about upscaling. It seems to be helping, but I don't know how consistent it will be.