why corepack is faster and fitgirl is smaller

[FitGirl]

Originally Posted by zoroX

You could say many of your modern "not so popular game" repacks. Most the popular game repacks done by you, even the modern ones are slower but off course smaller.

Only repacks with some custom compression/encryption, which require data rebuilding. Absolute majority of repackers can't do anything if game data is not supported by precomp/pzlib/ztool.