As academic with the tenure job, I don't think it gets easier with the tenure -- you'll have to do more non-research stuff, admin, teaching, supervisions, grading, grant writing etc. (some people like it, but I just prefer research)
I do have burn-out certainly that appeared after I had a faculty job for a few years. That mostly has affected my overtime research work, which previously would take most of my free-time, but now I try to spend more of my free time on hobbies.
My advice is that unless you can overcome burnout somehow, not to try tenure positions in the states, because there you'll have to work really hard to get to tenure. I think positions in Europe tend to be often tenured from the beginning (i.e. UK) so it may be easier.
(throwaway account)