VMWare just released(about 15hours ago) their new Performance Troubleshooting guide. This is a great guide that walks us through both causes and solutions, to many issues that us VMWare Admins see on a regular basis.
As they put it on page 7 of the guide:
This document covers performance troubleshooting in a vSphere environment. It uses a guided approach to lead the reader through the observable manifestations of complex hardware/software interactions in order to identify specific
performance problems. For each problem covered, it includes a discussion of the possible root-causes and solutions. In particular, this document covers performance troubleshooting on a VMware vSphere 4.1 host. It focuses on the
most common performance problems which affect an ESX host. Future updates will add more detailed performance information, including troubleshooting information for more advanced problems and multi-host vSphere deployments.
Long story short, check out the guide and VMWare’s blog post here to get the full story. Oh and just do yourself a favor and go pick up the guide 🙂