Too Old For Physics Theory?

How old is too old to do serious High Energy Physics? Is it true that most theorists work is done in their twenties and maybe thirties? Here is a Chart from Spires to help us out:
Fact: Half the authors were 32 or younger when they published their famous papers, and the largest group was 29-30.

It appears I will need to get my act together. If I get a PhD in 5-6 years then I will be doing my first postdoc during my "prime." Now I see why they said at the lab: "Work hard as a gradstudent, postdoc and new faculty member because that is when you will do your best physics." Being as most high energy theorists don't get tenure until their late thirties I can now see how true this can be.

Now we have to remember these only list top cited papers. Perhaps people in their post 40's years are publishing the most average cited papers. I don't know.

This is also why I was told go to a grad school where the faculty is young, fresh, and excited. They are the ones getting all the top citations.