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Fiddler adds a one second overhead on PUT requests

I've struggled debugging a slow put-request to our ASP.NET Core 2.0 Web API. After trying most things, I realized turning Fiddler off solved it. I've confirmed this, enabling the listener adds about 1s overhead to the request. This is only present for PUT requests.

POST-request with Fiddler on: ~20ms

Identical request with PUT, Fiddler on: ~1.200ms

Identical request with PUT, Fiddler off: ~20ms

  • Guest
  • Oct 25 2017
  • Needs review
Bug
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  • Eric Lawrence commented
    October 25, 2017 15:10

    It seems likely that your client application hasn't disabled ServicePointManager.Expect100Continue. Depending on your scenarios, you may wish to do so.

    See https://blogs.msdn.microsoft.com/fiddler/2011/11/05/net-httpwebrequests-and-expect-100-continue/