CompactGUI is a standalone GUI to make using the Windows 10 compact.exe function easier to use. This allows games, programs and other folders to be compressed transparently (i.e they can still be used normally) with no performance loss.This is similar to the NTFS-LZNT1 compression built-in to Windows (Right click Properties Compress to save space) however the newer algorithms that CompactGUI use were introduced in Windows 10 and are much more efficient, multi-threaded, and designed for use on executable programs resulting in greater compression ratios with almost no performance impact.Those with older HDDs may even see a decent performance gain in the form of reduced loading times as the smaller files means it takes less time to read programs and games into RAM