We've been running a suite of 14 websites in one Umbraco 4.0.4.2 instance in a production environment on a physical Windows 2008 Standard 32-bit server with 1 quad core CPU & 6 GB of RAM. For the past three years the sites have been running great without any performance concerns.

Our company was recently acquired and we have received the directive that we need to consolidate our current physical web environment in to their data center which is an entirely VMWare virtual environment.

So we ported the environment in to a duplicate VM environment in the new data center and we have been experiencing nothing but problems. Page load times that vary from an expected 2.5 seconds to over 18 seconds with just a couple of users on the box. We're able to bring the sites to a halt with a minimal amount of users during load testing and regardless of what we do we have been unable to duplicate the performance that we experienced on the physical hardware.

Does anyone out there have either experience running V4.0.x in a virtual environment or suggestions on what we can do from a tuning/configuration perspective to improve things?

Given the complexity of the websites and the desired timeline of the migration upgrading to a new version of Umbraco is a significant undertaking and one that is likely not feasible in the near term so I am hoping we can figure a way to make it work on 4.0.x.

Thanks!