1、运行，fiddler,选择Rules—>Cutomize Rules打开CustomRules.js 文档
2.修改如下图部分：
if (m_SimulateModem) {
// Delay sends by 300ms per KB uploaded.
oSession["request-trickle-delay"] = "300";
// Delay receives by 150ms per KB downloaded.
oSession["response-trickle-delay"] = "150";
}
request-trickle-delay中的值代表每KB的数据被上传时会被延时多少毫秒，
response-trickle-delay则对应下载时每KB的数据会被延时多少毫秒