The folder gets large, but that is because of all the patches that are applied to your installation. Do not simply delete the files, because it could cause all sorts of havoc. The only way to actually reduce the size somewhat, is to have Windows remove any previous updates after you install a service pack. You can do this with the following command. I was able to clean up 4GB using the command. Nothing major, but amost 25% improvement.
dism /online /cleanup-image /spsuperseded
Run as administrator.