Actually there are no concepts or even any kind of solid work not to say any prove of concepts in code on how to break privacy of PrivateSend. How slow it is? It is not supposed to be fast, it mixes the coins of different users and there are 4.7k masternodes those make it as fast as it possible with amount of rounds user sets in his/her payment. It takes those amount of rounds plus 6 confirmations for every round. You can't make it faster, because it is not supposed to.