A few months ago, New Relic introduced Real User Monitoring. It natively supports WordPress and Drupal as of the time of this writing. By “natively supports”, I mean you can just turn it on in the New Relic control panel and your web servers will start automatically injecting it into your pages’ head. Real User Monitoring works with any web app, however — you just have to manually add the code yourself.
Here’s how you add it to a Magento theme template.
Edit app/design/frontend/[your_interface]/[your_theme]/template/page/html/header.phtml and add this at the top:
if ( extension_loaded('newrelic') ) {
echo newrelic_get_browser_timing_header();
}
Edit app/design/frontend/[your_interface]/[your_theme]/template/page/html/footer.phtml and add this at the bottom:
if ( extension_loaded('newrelic') ) {
echo newrelic_get_browser_timing_footer();
}