Often this is the result of a problem with the installation. You don't mention whether you are using the Classic CC or the CC version of Lightroom but the procedure is the same.
Please follow these steps:
1. Uninstall Lightroom Classic CC from your Windows machine using the Creative Cloud App.
2. Restart your computer.
3. Open the Creative Cloud App and install via the App and it will use a fresh download.
After the reinstallation, do you still see the same same slow behavior?
Can you describe specifically what is slow? Is it importing? Scrolling a grid of thumbnails? Applying a spot brush? Something else. A specific example of behavior that is slow and an idea of how many seconds/minutes it takes will go a long way toward helping us diagnose your slowness. It will also allow us to test the operation and provide you with some comparison for what is expected.
Thanks for your help.
Adobe LR Classic
Nikon NEF to DNG at 6000 x 4000
1920 * 1200 DELL monitor
i9-9900 CPU at 3.6GHz with 16 cores and 5GHz top clock
nVidia 2080i GPU
Intel z390 mobo
OS and LR software on NVM M.2 drive
Images and Catalogs on SSD
Runs appallingly slowly. Takes 3 to 5 seconds to move from image to image, cursor lags inputs, processor permanently churning at about 5% in background (I left it running for 2 days, just in case it was face recognition ...)
So, frankly, its the software, guys. Lightroom used to be (on a much older PC) greased lightning fast. Something got broken in 2018, and if it means removing features, please speed it up before adding features. Speed matters.