Sounds like Oculus did some extensive logging on your machine.
Anyway, reminds me of a few weeks ago when I was desperately trying to find out what caused my SSD to run out of space. It was always too small but I managed. Recently, however, it had started filling up, and I had no idea why. I downloaded a program for checking what's using all the space, cleaned up some stuff that it found, but didn't really find anything too interesting at first. Then I found it: Atom (a text editor, you might say) had been keeping the data from old versions as it updated itself. I think there was more than 10 GB of data there, which isn't really all that much, but it makes a huge difference for my too small SSD.