It takes forever with me as well. Any project, even demo projects like Epic Zen Garden or SciFi Hallway can take 5 minutes or more to open. The Editor splash screen shows 94% for a loooooong time, and then it opens. Once it’s open I have no issues. It’s not laggy, the viewport is smooth and runs well.
I’m thinking that it’s doing some kind of online check that is maybe blocked by my firewall, and thus it has to time-out before continuing. Not sure where that would be though.