Uninstalling and re-installing never solved any problem if you don't purge it, you might have a corrupted file in your GIMP's profile
To check this out:
Close GIMP, rename the "2.10" folder with something like "bak.2.10", it should be somewhere like /home/YourName/.config/GIMP/2.10/ (I'm on Linux so the path is a bit different than Windosw, something like C:/Users/yourname/AppData/Roaming/Gimp/2.10 I see there
viewtopic.php?f=8&t=16545#p228367 or over there >
https://www.gimp.org/tutorials/GIMPProfile/ ), once it's renamed
Then start GIMP, this forces GIMP to re-built this directory, like the first time you started GIMP, it will (re)create a new "2.10" directory.
But if you have customized GIMP you will lose your all settings (it will look like the first time you opened it).
Try GIMP...
if it is still slow, then remove that new directory that GIMP created and and rename your "bak.2.10" to "2.10" to get back all your preferences and custom settings, or even faster -> if you did
not close that window directory "GIMP", just Ctrl+Z 2 or 3 times in that directory to get back the directory as original