@Bart_Vandewoestyne said:
we're storing our Qt build in our version management system
This is a strange thing to do, since Qt guarantees binary compatibility between minor versions, but well, you're free to choose. Unfortunately, I don't see how you could decrease the size further, beside deleting the docs, as the libraries are in the /lib directory and they're the next biggest size. Maybe store only the libs that you're using, i.e. these that you're going to deploy. No point in keeping QtXml if you're not using it, right?