You may always create a passworded game, writing the password in the game description and adding FAST PLAYERS ONLY, PLEASE!!!.
This is not a REAL limitation (anyone who REALLY wants to spoil your fun will be able to join anyway - in that case you have all the reasons to publicly complain about that/those player/s), but at least you can avoid slow movers signing in for your games just because they don't notice your warning.
Just a suggestion...