I disabled the driver, restarted my machine, and now the game runs fine. I went and checked my device manager, and somehow my Nvidia HD Audio driver was re-enabled. 11, around 7PM, I ran a map and noticed my performance turned into a sluggish slideshow when I opened a Legion.

He disabled his Nvidia Audio Device Drivers and experienced much better performance. I shared this fix with one of my Path of Exile buds, and he experienced the same benefits. This is an issue affecting many players, which most are probably blaming the game. This is where I learned of the performance fix. I achieved near similar results by disabling the 'Nvidia High Definition Audio' and 'Nvidia Virtual Audio Device' in windows Device Manager. I turned off sound effects and the game turned from a 1-5 FPS slideshow to smooth 60 fps, didn't matter what content I was doing. I learned about this performance issue after disabling the games sound effects in the productions_config.ini file. I didn't want to support the league because I thought it was the game, turns out it was my software configuration. I couldn't properly play, and as much I enjoyed Expedition as a league mechanic, it was unplayable performance wise.

I experienced this issue notably in patch 3.15, and I could barely play the league because when I tried to interact with any league mechanic, or tried to kill packs of monsters, my game would turn into a slideshow. As the title says, on my system the Nvidia Audio Device Driver causes severely degraded performance while playing PoE.

Nvidia high def audio