In web development, hydration and rehydration are two terms that often get used interchangeably. Although there is a distinction between the two, it’s not always clear to beginners what the difference is. Rehydration is the process of taking an HTML document originally written in JSON or XML and converting it back into an XML-like tree …
The Speed Index metric is the most basic and fundamental measurement of the performance of a website’s user experience. Google introduced this metric to help site owners track their mobile pages by using a star rating system: 5 stars for “above average,” 4 for “good,” 3 for “OK,” 2 stars for “underperforming” and 1 star …
Main thread work is any work that takes longer than a few milliseconds to complete. These are usually CPU-intensive tasks that cause a frame or animation on the webpage to lag. It’s always best to minimize and reduce main thread work because it can affect the user-experience of your website and app by decreasing the …
First Input Delay (FID) is a metric, from Google, coming into force in May 2021 as part of the Page Experience Update. The metric will measure the time it takes from the user presses a key on their device and when the keystroke is registered in a browser. FID is part of Google’s efforts to …
The Priority index rating (PRI) is used by developers to decide whether an asset should be deferred or inlined. Coupled with a ticket prioritization system, the PRI offers SEOs an opportunity to better engage with developers when it comes to optimizing JavaScript on a client’s website, and in theory with better collaboration will yield better …
TBT (total blocking time) is a metric found when optimising page load speeds. The TBT for a given page is calculated by adding up the time that is spent blocked (waiting for the network to catch up before proceeding) and the time that is spent loading. A TBT score of 0 means that there was …