You're welcome
I actually expected that to have a big impact for a while. I was reluctant to do it because it makes it a little harder to patch a calibre install, which was a facility used by some calibre developers to have users test small changes. However, I realized that thanks to windows exposing zip files as folders, it isn't that much harder. ANd it has the added benfit that any patches get automatically removed at the next upgrade, unlike with using them in unzipped form.
The only downside is that it is now not possible to install calibre in a folder with non ascii characters in its path.