I would suggest to check what needs updating before continuing. It's very tempting to include that -y flag but it's best to know in advanced about what is going to change. Even if you don't understand what it all means and it reads like gibberish at first, you'll get more used to it after some time.
Some updates that tend to take a lot of time are things like Libre Office which are quite large and include tons of smaller little packages and libraries for things like translations, etc. Another classic example are kernel updates which need to be compiled on the spot.
And, well, internet does sometimes slow down from time to time.