I noticed my C fisc is full, and it shouldn't have been. I went to empty my recycle bin and it had 40gb! of stuff, and when I clicked to empty it, since it was a slow process, I could see most if the files had the ".skse" extemsion.
The answer to the question is that SKSE may be filling the recycle bin with temporary files that it creates while running. It is recommended to disable the recycle bin for the SKSE folder to prevent this from happening.
