This test measures how long it takes to connect to your site and for one page to fully load. A very important value to pay attention is the "time to first byte", which gives us how long it took for the content to be sent back to browser to start processing the page. If you are using a CDN (Content Delivery Network), your connection time may be low, but if the time to first byte and total time is also not low, it will not give you much in terms of performance.