Updated to 20.5.1 on my 5600 xt, now the game stutters bad running 144 frames, with and without free sync, anti-lag, and enhanced sync. Tried rolling back to the previous driver, still stuttery on 144 frames. Fortnite now has bad frame drops even on old drivers.
Update: updated Windows 10, and used DDU to remove old Nvidia drivers, and did a factory reset of adrenalin on the standard settings. Fortnite's frames still drop, but nothing below 80 in-game. Apex Legends still fills a little sluggish, but still saw some improvements