While working on an engagement deploying a medium farm on Windows 2008 with no internet connection I noticed a considerable performance hit causing by check for publisher's certificate revocation which is on by default.
Basically by having this option set, all managed code go through a cert check against crl.microsoft.com (Certification revocation check) by .net runtime before startup. While disabling this option is not recommended for security reasons, for a development environment with no internet connectivity turning off this check should increase the overall performance.
In order to disable this option simply go to Internet Options and uncheck "Check for publisher's certificate revocation" under advanced tab.
As an alternative, adding the following line to Hosts file should also resolve the issue (Thanks to my friend Ashkan for the hint):