Are Your SharePoint 2010 / 2013 Sites Running Slowly?
If your SharePoint 2010 or 2013 sites run very slowly, you might have an issue with the trusted authority root certificate that is installed with SharePoint. The reason for this slowness, may be that the security mechanism is checking to see if the signer of the application components is trusted on your server. By default, the root certificate in the chain is not added to the Trusted Root Certificate Authorities store of the SharePoint servers, so local validation fails. The server then tries to locate the public root certificate, which may or may not succeed, but can take a long time. Typically, it appears that the operation completes anyway, and there are few if any log entries written to point you in the right direction, but the delay is very noticeable while the validation takes place.
Many folks have reprinted the text of this Microsoft Support article with screenshots and examples, so you can search the topic with your favorite search engine, but here is the Microsoft support link if you would prefer to go to the source.