I have a SharePoint 2013 Farm which is behind a secure firewall and has no internet access which includes a Web Application running over SSL.

We keep seeing the following error in the SharePoint ULS logs (*A certificate validation operation took milliseconds and has exceeded the execution time threshold*). The timeout is anytime from 10 - 70 seconds and every time causes the page load to pause (and sometimes timeout completely).

I have performed all of the following:

 - Added the following certificates into the Trusted Certification Authorities store on all servers:
  - SharePoint Root Authority (extracted from SPCertificateAuthority using PowerShell)
  - SSL Certs for Web App (both the wildcard cert and the parent chain certs)
 - Added the "generatePublisherEvidence" attribute to the machine.config on all web servers (value set to "False")
 - Set the Registry Key HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\WinTrust\Trust Providers\Software Publishing  to 146944 (certificate revocation check disabled)
 - Modified the local security policy and disabled "Network Retrieval" under Public Key Policies
 - Use NETSH commands to add the IIS SSL bindings with certificate revocation checks disabled
 - Added "127.0.0.1 crl.microsoft.com" to the HOSTS file on each server
 - Servers have all been rebooted

This is very slowly driving me mad. Does anyone have anything else I can try?