What GPU are you using? It shouldn't take more than a few seconds to generate dialog.
I should clarify, it isn't the dialogue that takes a long time to generate, that only takes 5-10 seconds, however the text speed on already generated dialogue is painfully slow and often takes longer then the actual generation did. But whenever a character starts to follow me, if I want to continue the conversation, I have to end the dialogue and then talk to them, but they get stuck "thinking" for 40 seconds to a minute or two.
You can semi speed up the text speed by holding down the left mouse button.
The follow mechanic is yeah, sometimes a big hit or miss. We're having a party and I say: "let's get this party started" suddenly everyone wants to follow me, but when I talk to X and they say let's go to Rosy's place, even after saying for the fifth time, come on, let's go follow me, nothing happens...
The "ask to follow you" button is a great idea, and I second it.