Web Performance Metrics Miss the Assistive Tech User
Scott Jehl suggests that common web performance markers like First Contentful Paint and Largest Contentful Paint fall short of describing the real experience for all site visitors. These figures are frequently positioned as readability signals, but they may not hold up for users of assistive technology (AT).
These metrics are often touted as measures of usability or meaning, but they are not necessarily meaningful for everyone. In particular, users relying on assistive technology (such as a screenreader) may not perceive steps in the page loading process until after the DOM is complete, or even later depending on how JavaScript may block that process.
The catch is that a page can remain inaccessible to AT users until it is fully interactive, especially since external scripts often deliver accessible interaction patterns. Jehl sketches how metrics could account for that, but his key reminder stands: your personal measurement and perception of a site may be only a partial view.
