If it is as you say, only the #1 result for searches that have a high probability of it being clicked, then it's generally fine with me. If they were blindly pre-loading the first few results, I'd have a problem.
I guess I should give Google more credit, and assume they're not idiots.
If you're worried about the technology itself being abused to DDOS people, I don't see how it enables any attack methods that didn't already exist.