Listen carefully- - - - -you do not have a short, nor an open circuit. You have enough current draw to make the circuit breaker built into the light switch cycle on and off. The fact that it takes some time to begin cycling means there is not a "short" in the classic sense of the term. A short would make the breaker begin cycling immediately, as soon as the lights were turned on. An "open" would keep the lights from operating at all. Do the lights flash when they're on low beam? If not, you need to start investigating the current draw ONLY in the high beam circuit. Forget about looking for parasitic drains or other extraneous Bovine Scatology. It's simply distracting you from finding the true cause of the problem.
Jerry
