Measurement of web page performance is critical when you need to track improvements and justify performance optimization budgets. Over the years, multitude of metrics were developed, from Time To First Byte and Page Load Time all the way to more modern and sophisticated metrics like Time to First Paint, ATF and Speed Index. Web browsers also added multiple APIs to allow more visibility into the stack with Navigation Timing, Resource Timing as well as User Timing APIs. The challenge with performance metrics is that they are all proxies for user experience and don’t necessarily translate directly into user satisfaction and business gains.
Sergey Chernyshev reviews the reasons why we need to track performance and introduces a new method for improving existing performance metrics using Heat Maps generated based on business requirements