Hello, dear Gearbox... [unreasonable low framerate]

Sorry for little passive agression in title, but I’m really dissapointed. In 2019 I bought Borderlands 3 Deluxe bundle in Steam, spent a lot of my current money for that moment. Despite the really boring beginning, I played few hours (16 in total) and then dropped. Then my current PC could run it at stable 40-50 fps at Medium-High setings, but… Today I downloaded game, started it… And it lagging, thahell lagging. 2-18 fps even in main menu. The normal fps for my system is 35-45. Where is my fps now? Wha sould, what can I do to fix this problem? Disabling texture streaming, oving to SSD doesn’t work. Other trival tweaks and solutions too. Game equally lagging at Ultra low and High settings, at 720p with 50% render. Drivers is updated today. This shouldn’t be like so.

MAIN QUESTION: Why it wasn’t lagging then and started it now? How to fix it?