This tutorial discussed how to work with date and time in JavaScript with and without external libraries. Working with dates is always painful in almost (if not all) programming languages.

Chrome JavaScript timer throttling: Google's tests show it saves up to 2 hours' battery life Chrome will soon throttle JavaScript timers in the background, so the browser uses significantly less ...

Executing JavaScript code will definitely involve the processor cache and a high-resolution timer is accessible via browser performance API.