Whenever (even hourly) I start GSX Update in the Installer, it is downloading and installing everything over and over again.
What do you mean with "downloading and installing everything" ? Everything, really ? It downloads and reinstall the whole GSX each time ?
Maybe you wanted to say "it downloads something", that's more normal and is what I see in your screenshot and, as explained here:
https://www.fsdreamteam.com/forum/index.php/topic,26826.msg179094.html#msg179094The Live Update now always downloads and installs a ZIP file of the current Jetway replacement files and the current Airport services, because we found this is way faster than checking every single file for updates. And as you can see in the update log, it correctly skips file for airports you have Disabled.