Windows folder is the system folder of win7, which contains very important system files, such as Fonts folder of the system, dynamic link library files of the system and installed software (System32 and SysWsow64 folders), database files of the registry, etc. These files will increase as you use the computer for more time. For the newly installed system, the size of the windows folder exceeds 10G. When you use it for a period of time, such as installing software, the software will copy the dynamic link library file to the system folder, write data to the registry, or install new fonts, which will lead to the increase of the system folder. Below is the size of win7 64-bit windows folder on my computer for your reference.