I run a XF forum on an Atom machine. It works great for serving up pages on a low traffic private forum but anything CPU intensive and it just starts crapping all over itself. Rebuilds after addon install, update, or uninstall takes ages.
Could I disable automatic rebuilding for addons then manually trigger a rebuild after I've finished updating my addons? Updating more than one at a time is a serious chore.
You can upload all of your files as normal, then browse your computer for the XML files. If you put all your XML files into one directory, it will install all of them first and only once that has finished will it perform a single rebuild.
You can even just browse your computer for all of the add-on ZIP files. It allows you to select multiple ZIP files, it will then extract them, copy all of the files, find the XML files automatically, install them and again only perform a single cache rebuild at the end.