Responsiveness of the throttle level

Drupal.org suffered from a short traffic burst destinating from a single IP (presumably a crawler) and it takes hours for the throttle level to be restored. The algorithm to decrease the throttle level is not sufficiently responsive in a situation like this. Decrementing the throttle level should not depend on cron but on the _same_ mechanism used to increment the throttle level. The query overhead of this approach is both configurable and neglectable.