Windows 10 Pro, Lightroom 8.3.1
I have been tagging faces and noticed after a while that LR has slower and slower redraws and general GUI response. Looking in the task manager, I see 1800 or so GDI handles in use. At start-up it is more like 670 handles.
After some playing around while watching the task manager, I blame the Navigator window. If I just mouse-over a dozen or so folder names, the Navigator window shows the first photo in each folder, and the GDI handle count jumps up by dozens. It is the same set of photos each time, so it isn't about caching of bitmaps, I don't think.
There may well be other handle leaks, but this is the most obvious one.
My system has 128GB of memory. In the Old Days of Windows, leaking a few hundred handles basically killed Windows. More recent versions claim to let you waste handles recklessly, but the truth is that programs get unacceptably slow pretty quickly if they leak.
For now the work-around is to close and re-open Lightroom. But you want to make it better, right? It is not a speedy program.