Web Performance Load Tester is a powerful and easy to use tool that will allow you to automate load testing and generate reports to help you analyze the Performance of a web site.
The 10 virtual user version, which is full featured, is free to use and is ideal for identifying pages that exceed a threshold value for further investigation.
The following message appears in the log files:
Could not create an instance of the counter 'XXX' (category: 'YYY')
Exception: System.UnauthorizedAccessException
Message: Access to the registry key 'Global' is denied.
Resolution:
A Sitecore application pool user has to be a member of the system "Performance Monitor Users" group to have access to the mentioned registry key. Adding the user to this group and restarting IIS should solve the problem.
" Speed Tracer is a tool to help you identify and fix performance problems in your web applications. It visualizes metrics that are taken from low level instrumentation points inside of the browser and analyzes them as your application runs. Speed Tracer is available as a Chrome extension and works on all platforms where extensions are currently supported (Windows and Linux). "
Page Speed is an open-source Firefox/Firebug Add-on. Webmasters and web developers can use Page Speed to evaluate the performance of their web pages and to get suggestions on how to improve them.