[Captain Kwok]

I agree and I want (and already had) to increase the map radius size - but I dropped it a bit to reduce the AI processing times since they might enter such a scenario a half-dozen times per turn etc. Anyhow brief testing seem to work well with 2000 for the size in a frigate vs colony type scenario. In the meantime you could use fighters to chase down enemy colonizers faster. Even a early freighter-carrier can carry a small complement of fighters for such a purpose.