Loading screen lag

The rest of the game runs fine, it's only the loading screens that I have a problem with. I've noticed that it's worse when I'm joining groups. In larger groups, like 24-person ones for world bosses, loading screens can take up to two minutes.

Based on answers to other help threads, I've uninstalled and reinstalled the game, verified file integrity on Steam, defragged my drive, set my power option to high performance, installed DX9, disabled hyperthreading, added DXVK, and made sure all my drivers are up to date. For ingame settings, nameplates and flytext are off, combat logging is off, and vsync is disabled.

I tried messing with other graphic settings, like turning off bloom and shadows, and it didn't help. I play fullscreen on high settings. My ping is under 30 and my hardware is well above the minimum requirements listed on the Steam page (haven't found hardware specs anywhere else) so I don't think my internet or computer have anything to do with it, especially since I run much more hardware-intensive games with better loading times.

What else is there to try? I'm at a loss.