Sending bytes over network

Hi

I'm building a server in java and the client is in unity3d. At the moment I'm sending data in json however the performance isn't great so I'm thinking of compacting the data I want to send in a raw bytes message I'm just not sure what would be the best format... I want to send position and rotation and on other occasions I want to be able to pass on methods. I'm guessing I will need something like Client id, event Id and then parameters.

Also for some reason the moving of the player is very laggy even if there is only two players, I can provide the code if anyone can have a look into that.

Any examples would be great thanks