Why does windows 7 "write" that it took up 27.9 GB, when in fact the size of the files on the disk does not exceed 15.2 GB?

Question

boot camp

Installing Windows 7 Enterprise x64 on MacBook Pro retina 13 (late 2013) via bootcamp. When installing for the first time, I allocated 20 GB for the system, since I will use it very rarely, but it's a pity for the place. About 4GB remained free. Having decided that 20 GB is still not enough, I decided to reinstall it, allocating 30 GB. Of these, 2.57 GB were free! At the same time, if you reflect hidden files and folders, it turns out that only 15.2 GB is occupied. Why is this happening and what to do about it?
PS I did the same procedure on the same poppy with the same windows (only ssd 128 gb), 10 GB remained free.

Answer 1

here C:\Windows\winsxs hardlinks and there are a lot of them

Answer 2

Sorry for the stupid question, but what to do with them? :D delete?