Bad news I'm afraid.
It's definitely the number of names in the list that causes the problem.
The list of first names is easy to pare down just by removing duplicates in equal proportions, and all of the nick names (eg, Joe, Frank, Bill) that have proper name equivalents in the list (eg, Joseph, Francis or Franklin, William).
Unfortunately, the list of last names is not so easy. I first tried reducing the proprtions of the duplicates to about a half, then a third, but it was still too many. Then I removed ALL the duplicates, and it's still too big.
So unless you want to start dropping names entirely (which I understand is not in the spirit of the thing) there's no way that I can see to make it work.
I tried....
JD