IIS7 設置gzip 後測試發現有時生效有時不生效原因

IIS7中開啓了gzip後，工作機制是如果訪問次數在規定的時間內沒有超過多少次，就不啓用gzip，例如

以下表示在5秒內訪問次數超過10次就啓用gzip

determining factor for a return value of true is two requests in a 10-second time span. You can configure this behavior by modifying the frequentHitThreshold and frequentHitTimePeriod attributes of the <serverRuntime> element in your ApplicationHost.config file. For example, to configure your server to return a value of true when a URL has been requested 10 times in a 5-second period, you would modify the <serverRuntime> element in your ApplicationHost.config file by adding the following attributes:

<serverRuntime
    frequentHitThreshold="10"
    frequentHitTimePeriod="00:00:05" />