http://bugs.winehq.org/show_bug.cgi?id=58155
--- Comment #12 from ToastyBug cemer99797@isorax.com --- Brendan Shanks comment #8:
Populating a new prefix is done by wineboot (with a lot of code also in setupapi), and it's quite complicated. Improving prefix creation (both in speed and disk space) is something I'd like to do, but there's no low-hanging fruit I've found yet.
Instead of using wineboot to populate a new WINEPREFIX, can it be done with standard Unix tools for Linux and macOS? And once the prefix is created, wineboot (or whichever wine exectuable is appropriate) could take over.
Could this be tested by manually copying all the correct files with the macOS Finder from Wine.app/Contents/Resources/wine/lib/wine/ to $WINEPREFIX/drive_c/windows/? Does it work in such a case?
If instead of plain copying, wineboot has to create files that are not binary-identical to those included in Wine.app, could the files that belong in the WINEPREFIX instead be included in the Wine.app binary build, and the APFS cloning method used to populate the WINEPREFIX?
Linux also supports CoW with the XFS and BTRFS filesystems. Does Linux also take up an additional ~300 MB per WINEPREFIX?