Intermittant slowdown issues for SharePoint (Pt 1/3)

A SharePoint server that does not have internet access can experience intermittent slowdown issues. I’ve been experiencing this in the following situations

• Long page load times on initial site access.
• Long search times.

Note that in both these cases, after the initial slow page load, a user will not experience problems until their IIS session expires – they’ll have the problem again the first time they use SharePoint after that.

There appears to be two related causes for these issues – both caused by the server not being able to communicate with the internet.

STS Certificate authentication

This appears to be an issue when using claims-based authentication. The SharePoint Security Token Service (STS) uses certificates – the validity of the certificate has to be verified on a periodic basis to ensure that the certificate has not been revoked.

By default, the CRL check for the certificate is performed over the internet (http://crm.microsoft.com/). If the online CRL server cannot be reached from the SharePoint server, the operation times out after 15 seconds by default. Even if the CRL validation fails after 15 seconds, the SharePoint page may still be rendered after the delay.

Certificate Revocation List (CRL) checking

When starting a .NET application, the .NET Framework will attempt to download the Certificate Revocation list (CRL) for any signed assembly. If the server does not have access to the Internet, or is restricted from accessing the Microsoft.com domain, this may delay loading of the assemblies.