I hope it happened only once.

No, this happens every time I use auto-updater. I used it 4 or 5 times when updating to the newer EmEditor RC releases, and each time it took equally long time to update. This time, however, I was finally annoyed enough to overcome my laziness and report about it.

Maybe buffer sizes are not good enough?
And what is the exact URL location used for auto-updating? Maybe, this is just a different server which has a different route from/to my computer with some very slow node in between…