Lower TTFB with asp.net 4 and App Insights installed on win 2016 server RRS feed

  • Question

  • User-1050699783 posted

    We have a VM on Azure with Windows Server 2016 and IIS v 10. We have hosted a Dotnetnuke based website( Framework 4.5.1)  for asp.net 4.0  app pool framework which uses SQL 2016 as backend. We are facing a strange behavior on this newly created server and hope that you will provide some insight to it.

     Problem Statement:

    Normally this combination of frontend and backend renders our website with a TTFB ( Time to First Byte) around 2 seconds in a logged in user scenario. However when we install “Azure Application Insights” on this machine ( only installation and not enabling it) and restart the server, the TTFB automatically comes to about 500 ms in a logged in user scenario. We tried to compare any changes made to machine.config etc. during this installation but could not observe any. Could you please analyse and suggest what could have caused this behavior? The moment we uninstall “Azure Application Insights”  and restart machine, TTFB again increases to 2 seconds.

    Any suggestions on this will be extremely helpful. Thanks

    Monday, August 14, 2017 11:15 AM

All replies

  • User283571144 posted

    Hi devrishi,

    Could you please tell me how you install the “Azure Application Insights” on the server? By using this way(enable Application Insights by using Status Monitor.)  or this way?

    I guess the AI will continue working to collect the data , so it will auto warm up your IIS application. You will find it works faster then doesn't install it.

    Best Regards,



    Tuesday, August 15, 2017 6:51 AM
  • User-1050699783 posted

    Hi Brando,

    We do install it using "ApplicationInsightsStatusMonitor" installer on VM. Please note that we just installed it and did not enable it for any of the website configured in IIS, even then it does this "miracle" thing. I was curious to know, what  general steps are performed when this application installer executes as this process might have tweaked some settings or some ports etc. that causes faster TTFB.

    The moment we uninstall it and restart VM, TTFB is back to 2 seconds from 500 ms.

    Thanks for looking into this.


    Wednesday, August 16, 2017 4:51 AM
  • User1771544211 posted

    Hi devrishi,

    Have you tried the IIS Failed Request Tracing to get the detailed information of the execute process of the request?

    You can use the IIS failed request tracing to check the time taken in each process of the IIS work flow. You can find how to use failed request tracing in the following link.


    Best Regards,


    Wednesday, August 23, 2017 7:20 AM