Many people make a new thread, because the zombies/player are laggy, but there´s a solution already out! So may they look here before posting :)

Open your WarZ_Server.sln

file: obj_ServerPlayer.cpp
Find:
gKeepAliveReporter.SetStarted(true);

change:
::Sleep(10);		// limit to 100 FPS

ServerGame.cpp
find:
if(curTime > lastVisUpdateTime_ + 0.3f)

and change it to:
if(curTime > lastVisUpdateTime_ + 10.0f)