EC2 推出的新功能：「Amazon EC2 Auto Scaling introduces Warm Pools to accelerate scale out while saving money」。
重點只有這個，這個作法是先把機器準備好，然後關掉放在 stopped 狀態：
Additionally, Warm Pools offer a way to save compute costs by placing pre-initialized instances in a stopped state.
理論上可以快到 30 秒：
Now, these applications can start pre-initialized, stopped instances to serve traffic in as low as 30 seconds.
不過考慮到就算是 stopped 的機器，啟動時還是得去確認有沒有新版程式... 目前可以理解的部份，應該是加快 EBS 的準備時間吧？