Balanced Round Robin Pairing
Currently, Round Robin Pairing is "greedy". This means that the game just starts looking for games and as soon as it finds valid games, those games are locked in.
This might mean that players might get paired at all at first, which is not a necessary thing if a more balanced pairing algorithm was used.
The problem is rather visible when running a Round Robin tournament with 4 players and up to 2 games at a time, where you will find that every player starts off with two games, except the last player, who doesn't get to play in any game until other games have finished. (I think it might just happen with any tournament involving n players and n - 2 matches per person.)
As such, it would be better to have a better Round Robin Pairing algorithm.