“tar extracts in quadratic time, stuff like that”. Is that what your favorite clanker told you? If that’s the case, why is uncompressed tar almost instant in practice when others take many seconds? Or compressed tars in the same time neighborhood than any other tool?

Who does “quick lookups” in an arcived file? At most a content listing and then parse/grep whatever you want.

About cat: Sure bud, but go and reconstruct a folder after you cated it.