The problem is not the lag before resolving the request, it's the lag the user finding out that the request will not be solved. Underlying this is the fact that the server simply does not have enough power to resolve all requests, so some must fail.

The trick of using event loop lag is pretty neat, but the general strategy is IMHO a must have for any service. By aborting early and somewhat gracefully, the user knows ASAP, receives a controlled message that suggests she should not quickly retry, and the server can avoid trying to do part of the work for the request that is not going to be completed.