Sudden large performance drop in UE

UE has been running OK, but a couple of days everything slowed right down.

I just closed UE and thought it’d probably go away, but still UE4 is running at a crawl.

With just a few objects and a flat landscape I’m getting about 7 FPS in the editor window.

My computer isn’t particular taxed, about 25% CPU and 33% memory, but the engine is running slow.

I haven’t knowningl changed anything on my computer on in unreal, and this is affecting multiple projects not just one.

Can anyone help figure out what it is?

I backed up my projects and reinstalled everything and it’s good, back to 60 FPS