See http://stackoverflow.com/questions/28723222/timeoutexceptions-from-mongo-c-sharp-driver-with-async-api.

There is a configuration option for raising this higher (MongoClientOptions.OperationTimeout) -> https://github.com/mongodb/mongo-csharp-driver/blob/master/src/MongoDB.Driver/MongoClientSettings.cs#L254

This might just be a case where it used to take this long with 1.x, but there were no timeouts in the 1.x side of things.