I have two identical (well, almost) environments and one is slower than the other one. I have been testing a OOTB site collection on each environment and one performs slower than the other.

Using fiddler I see that in the response codes I get 12 http/401

HTTP/200:   63
HTTP/401:   12
HTTP/304:   1

In the other one I get just 1.

HTTP/200:   72
HTTP/401:   2
HTTP/304:   1

Does this code 401 slow down my page? Some of the links that throw the 401 are:


Is there anyone who would like to have a look at the Fiddler Sessions? I can email them to you.

closed as off-topic by moe, Asad Refai, Mike, Gaurravs, Dikesh Gandhi Nov 29 '17 at 4:17

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When using NTLM, requests will generate a 401 as IIS must communicate with a DC each time a request is made. For security reasons primarily, but also performance reasons, it is strongly recommended that you switch to Kerberos authentication for all Web Applications. This will reduce the number of 401s encountered.

That said, the 401s aren't going to add any significant overhead to any one request.


I would say yes, as 401 means that user getting access denied to the resources he is trying to access. it tries couple of time before giving up so thats why you are seeing too many 401 error. one http 200 vs couple of http 401 may cause the page load performance if you are using the NTLM authentication, we experience notably difference.

You have to fix the access to those objects. You can also enabled the Developer Dashboard on the site collection, which will tell you on which object it is spending more time.

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