Performed a hard reset on my HTC 8X, and system takes 4.57 GB (WOW...)
Stick to the question, PLEASE
I live in Romania and I use Orange. 8X 16GB Version.
Try clearing IE history, it might go down. Plus even though temp files say 0 bytes still clean it, it'll clear up some space which shows in the overall free space capacity increase
If you are in developer preview is going to take a lot of your internal space.. Maybe you should try by reinstalling your firmware with Nokia care suite or recovery tools..