If I switch regions in the launcher, every single time it has to patch some small amount of data (I assume its the localization differences). Is there some way to avoid this, short of having multiple program installs?
Every time you click "change region" in your launcher the program need to check all the files in your directory, to make sure your version is the same as the current version.
This is needed because when you update your patch, you are only downloading the files of your current region. For example, if I'm playing in the NA server and them I change my region to Brazil, the launcher will check all my files and download any files that are different, like voices files, because the language is not the same and the files are differents.
But once the launcher has finished the download, you can change regions and your patch will be up to date.
But there is no way you can prevent the laucher for checking your files every time you change regions.