I am using Cura to slice for an Ultimaker 3. For some reason, Cura becomes unusably slow (having to wait for a minute or more between mouse clicks) when I have it connected to the internet. As soon as I disconnect my computer from the internet, it returns to the normal speed. I assume this it has something to do with Cura trying to connect to a service and getting a bad response? Either way, this issue happens on both my macbook and PC, as well as across Cura versions (I have tried 2.3, 3.0, and 3.1).
Disconnecting from the internet to use Cura works in the meantime, but it means I cannot view my printer over the air, nor send prints wirelessly. It would be nice to have this functionality.