Latency is caused by the speed of light, and that's a problem because you can't change it. Large latency means users get tired of waiting for your page.
How do we fix it? We learn from computer history. Cache, parallelise, predict. We also need to measure. That's where boomerang comes in.
Boomerang measures your site's performance from the end user's point of view.
Clipping is a handy way to collect important slides you want to go back to later.