I got an XPS 15 3 years ago. I think it had Windows 7 at the time so I've had it install every upgrade from Windows 8 to Windows 10.
Lately it's become ridiculously slow - taking 30 seconds or more to open a small folder even though it has SSD, lots of ram, and I'm barely running anything most of the time. There is clearly some kind of configuration problem that got messed up over time.
I'd like to re-install Windows but I'm not sure what will happen. Will it install Windows 7 from the original image? Will that upgrade to Windows 10 directly? Is that still free?