On one hand, sure, it could go faster. But on the other hand, I think they need to do a bunch more reconnecting before moving forward in the relationship. It's not like they lack the time, or there's any fear of anyone else getting in the way (and if there is, it's just unneeded, artificial drama).
I mean, they're still too awkward to hold a proper conversation half the time. They don't know that much about who the other one grew up to be. Who they really are, not the persona they're currently presenting.
Right now, I think she's the one holding them back the most, since she's giving mixed signals by asking to go forward more than she's even comfortable with as jokes, and at the same time downplaying her own feelings. He seems to mostly try to adjust and make sense of where she actually stands.
And making sense of each other is helped just a little bit by honesty and trust, which they currently lack.