When you press lightning shield, all of your instances react at the same time, so you see the lightning effect immediately. The issue with targeting is due to server-client lag. I'm assuming you clones are assisting your main in one for or another (targettarget, focustarget, assist / target, etc). So what happens is this: Your main switches targets instantly, and sends that information to the server, then the server will broadcast that information down to all the clients nearby. So when you switch targets and immediately go to cast a spell, your main will have the new target, however your slaves won't see the new target until they receive the information from the server.

The reason for this is that it makes more sense to broadcast target information to the clients, rather than having the clients query for it. If that was the case, then you'd have noticeable lag in every spell that you cast.

So it's not a problem in keyclone or a problem in your computer. It's simply the way the client-server architecture is designed.