I've noticed this and in my case it's more a matter of mindset than anything else. My day job consists of programming, and at night I do public speaking.

I find it takes me longer to get into a flow state when doing public speaking. I think the terms sometimes used are "up time" and "down time".

Practice definitely helps. I've taken improvisational acting classes and those were slightly helpful. I've learned to recognize when I feel I'm inside my own head. It feels like you know how you want to come across but actually speaking doesn't come out how you expect and you start focusing inward. The only way through it is to keep pushing yourself. Overload your senses by speaking through the situation and then volunteer to do more immediately after.

I've also found that being in a social situation when I'm internally focused will lead to fatigue, but if I take an active lead, then I get revitalized quickly.