Ping is raised based on the amount congestion and interference throughout the network, essentially a single user has to network data from his end to the server and the server back to everyone else which sounds complex but is very simple until you start throwing larger size content into those request, for example spawning 100 droids has to be networked to everyone on all their movements which causes congestion.
If your wanting to decrease ping then I advise you lower content count and limit your permanent prop's on your maps and entities/npc's that are placed. These are all networked between the server and the client. So don't setup everyone at once but set it up as you go. There is really no way to just lower ping on the spot unless your using a terrible congested server especially its on a shared server.