Slow RDP connection due to Root Certificate Update
Say you have a Windows server in a secure environment, with no internet access. When you RDP to another host in the same environment, chances are the initial connection is slow. The reason is simple. You host is trying to update it's root certificates and check they are still valid by getting a CRL. With no internet access, that's a bit hard. As this will never succeed, you may as well disable it:
1. Run gpedit.msc
2. Open the following settings, Computer Configuration -> Administrative Templates -> System -> Internet Communication Management -> Internet Communication Settings
3. Enable the Turn off Automatic Root Certificates Update setting.
Now RDP connection should be nice and quick :-)