See also here: Lightroom Performance - What's Slow? | The Lightroom Queen
What happened on your system 3 weeks ago before the slowness appears?
Unfortunately you haven't given us any information about your system. Therefore, all proposed solutions are a look into the crystal ball.Please provide a copy of your 'System Info'. This can be get from the Lightroom menu item Help > System Info. There's a copy button in the System Info dialog. Press this button and paste the info into your next forum post.
Is your system up-to-date? Do you have installed all recent updates and patches for the operating system and the device drivers, especially the graphic driver. Please make also sure that you have installed the Studio version and not the Game Ready version of your NVidia driver.
My System: Intel i7-8700K - 64GB RAM - NVidia Geforce RTX 3060 - Windows 11 Pro 26H2 -- LR-Classic 15 - Photoshop 27 - Nik Collection 9 - PureRAW 6 - Topaz Photo AI