When I am here in Botswana, I have poor slow internet which makes things very difficult. Also Construct 3 needs internet to work online.
However, there is an offline option too, which makes that when you have no internet, you still can use Construct 3. For this to work, you need to make sure that the offline version is downloaded to your local disk. This you can do with the combination "CTRL" + "F5". After a while you see in the left bottom corner a message in a blue dialog that the offline version is downloaded. This is very important, always make sure you have the offline version downloaded.
When your internet is poor or slow, Construct 3 seems to load forever. You can wait, wait, wait and keep waiting. Now before you start Construct 3, just disable or disconnect your internet. Then start Construct 3 the normal way you always do.
Bingo!!! Now Construct 3 loads from your local disk and you can continue exciting game development.