So today I played for a bit before the maintenance - game was running buttery smooth. Logged back in after it was over - massive stuttering and freezes, especially during combat. It is pretty much unplayable.
This happened to me as well, been playing with no performance issues since early launch and today after maintenance I had massive stuttering.
Closed my game soon after maintenance to do a restart and a steam file integrity check , it did not help.
After a little search now, it seems an active chat tab causes it apparently , which I can believe since there was a similar issue in the beta. So I’ll try making a custom tab with no area chat.
Other things I read were turning off Vertical sync from your nvidia panel or amd equivalent , or moving the installation folder to another drive.
Hope one of those work for you, I logged out for the day so can’t test them.