module.exports.loop = function () {
  console.log("Tick: ");
  var CPU_LIMIT = Game.cpuLimit;
  console.log(Game.getUsedCpu()+"/"+CPU_LIMIT);
  for(var i in Memory.creeps) {
    if(!Game.creeps[i]) {
        delete Memory.creeps[i];
    }
  }
  console.log(Game.getUsedCpu()+"/"+CPU_LIMIT);
}

This produces huge differences in cpu time used from ~1 to ~20.
Also the cpu usage is already very high at the first log already...

Is this normal behaviour?