Google has a lot of content, for example "Chrome DevTools => Analyze Runtime Performance =>
Get Started With Analyzing Runtime Performance" [0].
But an important piece of advice is at the bottom of one of their pages [1]: "Avoid micro-optimizing your JavaScript". Apart from their argument there, keep in mind you are programming for a number of very different runtime environments. An optimization that gives you a big boost in one implementation may slow you down on another one. That is true not just between various vendors but also among runtime versions from the same vendor.
But an important piece of advice is at the bottom of one of their pages [1]: "Avoid micro-optimizing your JavaScript". Apart from their argument there, keep in mind you are programming for a number of very different runtime environments. An optimization that gives you a big boost in one implementation may slow you down on another one. That is true not just between various vendors but also among runtime versions from the same vendor.
[0] https://developers.google.com/web/tools/chrome-devtools/eval...
[1] https://developers.google.com/web/fundamentals/performance/r...