Our speed testing tool of choice is Pingdom – tools.pingdom.com
Pingdom gives us the actual load speed which is what we’re focussed on. Many other speed tools spit out a bunch of technical recommendations many of which have very little impact on speed at all.
After working with thousands of sites we’ve found Pingdom is the most accurate measure of speed and allows us to test speed from multiple geographic locations which gives us a better picture of how your website is performing in the real world.