The Performance Checker measures different metrics that are responsible for the time a website needs to load. The required load time of the metrics is considered too long if it exceeds the entered load time (in milliseconds).
To generate a positive user experience, the loading time should be as short as possible.
Time to first byte (TTFB) describes the duration from the user or client making an HTTP request to the first byte of the page being received by the client's browser.
Time to load is the time required by the browser to display a web page completely, including stylesheets images and all other dependent resources.
As some websites never stop rendering or loading Leankoala has a standard timeout of 30 seconds. If the browser does not fire the load event within the given time Leankoala is not able to provide the "time to load" metric.
Time to first contentful paint (FCP) measures the time from navigation to the time when the browser renders the first bit of content from the DOM. This is an important milestone for users because it provides feedback that the page is actually loading.
- The page has displayed useful content, which is measured with First Contentful Paint.
- Event handlers are registered for most visible page elements.
- The page responds to user interactions within 50 milliseconds.
Leankoala collects the data required for this purpose by running Google Lighthouse.
The metrics Time to first contentful paint and Time to interactive are checked by Leankoala once per day. Basic metrics like Time to first byte or Time to load will be checked once per hour.