Where does BTT updates download from? Downloads seem quite slow.

It always seems extremely slow--US user here with gigabit ethernet. I download system updates, App Store updates in seconds, and most other apps that want updates like Al Dente, Bartender, etc all go really fast.

But somehow BTT always takes forever to download. With luck sometimes it's 1-2 minutes for the download of ~30 MB, but right now I'm waiting and watch it tick 0.1 MB every 3 seconds. Painfully slow.

Are download servers only in Europe?

yes my server is located in germany, for the stable release channel providers around the world usually cache the files at their location. For alpha or manual updates usually not