Real User Monitoring gives insight into performance for actual users visiting the website.
https://www.pingdom.com/rum/
Analytics and Tracking · Application Performance
Get access to data on 606,393 websites that are Pingdom RUM Customers. We know of 26,011 live websites using Pingdom RUM and an additional 580,382 sites that used Pingdom RUM historically and 15,459 websites in the United States.
Get a list of 606,393 websites using Pingdom RUM which includes location information, hosting data, contact details, 26,011 currently live websites and an additional 500,186 domains that redirect to sites in this list. 580,382 sites that used this technology previously and 15,459 websites in the United States currently using Pingdom RUM.