Big performance issues after about 70 minutes in game - Technical Support - Last Epoch Forums
I was having same issues (in the post i detailed it).
I think i found a solution related to shader cache size, i posted step-by-step for NVIDIA and AMD. Hope can help you.
Update: Got it! look here:
“For anyone curious. Type windows key plus R. Type “services.msc” Then find windows error reporting. Right click on it and select properties. If it’s running, make it stop. If it isn’t, click on the trigger and select disabled in the drop down menu. This cleared up my problem 100 percent.”
(https://www.reddit.com/r/LastEpoch/comments/1mwyx4k/stuck_at_login_screen/)
i reinstalled game, reinstallted drivers, go to minimum graphic setup, distable Steam overlay and Game Recording … I even tried the C++ update and it still DID NOT WORK (!) … i have 1-2 fps in menu, absolutley unplayable.
System:
Ryzen 5 7600
GTX 4070 Super (updated Driver 581.08 - 19. August 2025)
32 GB DDR6 Ram
Win11 Pro
Last Season run with 100 fps+ with absolutely no performance issues, lags etc. - Please EHG Fix this fast!! 
I have the same issue as well.