In your analogy: your faster algorithm is probably not optimal. Sharing it with some people who can give feedback will make it better. Those people are probably not your competition, and your competition can talk to those people even if you don't. If the algorithm is going to make that much difference, then if your competition aren't working on it they're incompetent, and if they are working on it then who's to say they haven't got the better version already?

Your losses from sharing the algorithm are negligible (because the competition are either incompetent or working on it themselves) but your benefits from sharing and getting feedback are large.