Optimize First Input Delay
How to respond faster to user interactions.
Use web workers to run JavaScript off the browser's main thread
An off-main-thread architecture can significantly improve your app's reliability and user experience.
Avoid large, complex layouts and layout thrashing
Layout is where the browser figures out the geometric information for elements - their size and location in the page. Each element will have explicit or implicit sizing information based on the CSS that was used, the contents of the element, or a parent element. The process is called Layout in Chrome.
Reduce the scope and complexity of style calculations
JavaScript is often the trigger for visual changes. Sometimes that's directly through style manipulations, and sometimes it's calculations that will result in visual changes, like searching or sorting some data. Badly-timed or long-running JavaScript can be a common cause of performance issues, and you should look to minimize its impact where you can.