What causes a plane to snap when a lot elevator is abruptly applied at hight speed?

What is more prone to cause a high speed snap, being nose or tail heavy?

the reason i ask is because i maidened a NM extra 260, and the only bad tendency i found in it was that it snapped when i pulled back on high rates.... is there anything i can do to get rid it(HS snap) other than not doing it at all?

e.r.