Google has indicated that site speed (and as a result, page speed) is one of the signals used by its algorithm to rank pages. And research has shown that Google might be specifically measuring time to first byte as when it considers page speed.
Enable compression
Use Gzip, a software application for file compression, to reduce the size of your CSS, HTML, and JavaScript files that are larger than 150 bytes. Do not use gzip on image files. Instead, compress these in a program like Photoshop where you can retain control over the quality of the image. See “Optimize images” below.
Minify CSS, JavaScript, and HTML
By optimizing your code (including removing spaces, commas, and other unnecessary characters), you can dramatically increase your page speed. Also remove code comments, formatting, and unused code. BestWeb recommends using CSSNano and UglifyJS.
Remove render-blocking JavaScript
Browsers have to build a DOM tree by parsing HTML before they can render a page. If your browser encounters a script during this process, it has to stop and execute it before it can continue. BestWeb suggests avoiding and minimizing the use of blocking JavaScript.
Improve server response time
Your server response time is affected by the amount of traffic you receive, the resources each page uses, the software your server uses, and the hosting solution you use. To improve your server response time, look for performance bottlenecks like slow database queries, slow routing, or a lack of adequate memory and fix them. The optimal server response time is under 200ms. Learn more about optimizing your time to first byte.
Optimize images
Be sure that your images are no larger than they need to be, that they are in the right file format (PNGs are generally better for graphics with fewer than 16 colors while JPEGs are generally better for photographs) and that they are compressed for the web.