Couple of notes:

1) /focus only works on group members (not being pedantic...just FYI :P)
2) Look at your latency. Take that number, divide it by 100 and that's roughly what you can expect the client-to-server-and-back-to-client delay to be. So, if your latency is sitting at 150ms, it'll take an average of 1.5 seconds for things to update from one client to the other. This includes selecting new targets. Factor this into your play and you should be golden.