1.打开Fiddler,菜单栏： Rules->Performance->勾选 Simulate Modem Speeds 启用限速
2.修改默认限速，Rules->Customize Rules… 或快捷键 Ctrl+R ，通过快捷键 Ctrl+F ,搜索：m_SimulateModem 。
// Delay sends by 300ms per KB uploaded. 上传每KB需要0.3s。
oSession["request-trickle-delay"] = "300";
// Delay receives by 150ms per KB downloaded. 下载每KB需要0.15s。
oSession["response-trickle-delay"] = "150";
