Batclient is slower and laggier than most other clients. This is something that most players who have started with other clients agree on. For some players its the sole reason for not using Batclient. Every fraction of a second is important when you are fighting an eq mob.

At least some of the sluggish feeling comes from the fact that the client becomes totally unresponsive for short amounts of time when there is a lot of communication between the client and the server. You can test this by going to Arelium church altar and doing 4x "20 e" with verbose mode on. Your command line will freeze for a moment and for example Windows will mark Batclient as not responding for a moment. This is a clear indication that the GUI of Batclient has not been correctly separated from the model it runs on. It is also a sign of poor UI design which should be addressed as soon as possible. Time consuming operations which block the executing thread should not be run on the GUI thread. Fix that and the client will remain responsive all the time.

In fact, I dare say that there is a strong possibility that fixing the threading issue will completely remove the laggy feeling of the client. I hope that this issue would actually be addressed instead of just insisting that the client is as fast as possible.