Measure performance often

From the beginning of your project, regular performance measurement using several tools are key to regularly measure your page load performance.

If you are using http://www.webpagetest.org, you should target a maximum speed index metric of 3000, ideally striving for a value of less than 2000. Web Page test can show you how much content you are loading and how your site appears from multiple locations and in multiple devices. You should also consider using the Chrome Developer Tools timeline to review how different elements in your pages load under different circumstances, Google Page Speed, as a best practices reporting tool, and the Chrome Lighthouse extension to perform an audit of performance, SEO, accessibility, etc., and provide a best practices report.

After you go live with you project, Chrome User Experience reports can show you real world measurements of site performance.

Use of these tools and your implementation of the recommendations that follow in this chapter are your best chance of improving your customer experience.