當客戶反饋回來有performance問題時,你首先要做的是be able to reproduce and measure it. 然後才是改code,這樣你才知道自己所改的是不是真的提高了performance. 你的做法倒過來了,改了code又沒measure還倒至crash. 所以他有點不高興說this should not happen.