For me Live Update helped but I hope I don't have to do this frequently, it took like 30-35 minutes to download everything again
Apart for the fact that it takes about 6 minutes to reinstall GSX from scratch:
https://youtu.be/5oHiuDoZB1IThis is with a 1Gbit/s connection so, make the comparison with your internet speed to see if it matches up (for example, should take 30 min. with a 200 Mbit/s connection).
But that's not really the point. The point is, after you run an Update, if you run it *again* it should not download ANYTHING until we'll release a new update!
Why not just md5 hash and only download what's not matching?
That's exactly what it does, of course. How else you think it would be capable to download only what is required? That what normally does.