What is compatibility mode?

There are three test modes built into Calibre that ensure each Snapshot returns key performance metrics, even in cases when Lighthouse raises an error.

Generally these errors occur when a page has a set of characteristics, some of which are:

  • 10,000+ DOM nodes
  • Excessive main thread activity
  • Activity that causes Chrome browser to become unstable

By default, all Calibre tests run in Standard Mode, however in the event that a test fails due to a Lighthouse Timeout Error, Calibre will automatically re-run the test in Compatibility Mode.

Standard Mode

This is the default mode for all Calibre tests. All audits, metrics and artifacts are recorded.

Compatibility Mode

Compatibility Mode omits known problematic Lighthouse audits in an attempt to ensure the test completes successfully and performance metrics are recorded.

There are two stages of compatibility mode: Reduced Audits and Minimum Audits.

Test audits or artifactsPresent in Reduced Audits?Present in Minimum Audits?
Performance AuditsYesYes
Accessibility AuditsNoNo
Best Practices AuditsNoNo
SEO AuditsNoNo
Third Party AuditsYesNo
Main Thread Execution TimelineYesNo

Reduced Audits

Reduced Audits is the first compatibility mode. This mode will omit all non-performance related metrics, which means your test result return all paint based, runtime, byte size and request based metrics but will not return Accessibility, SEO or Best Practices scores and audits.

Minimum Audits

Minimum Audits is an alternate compatibility mode. In addition to omitting all non-performance-related metrics like in Reduced Audits, this mode will not generate a Main Thread Execution Timeline or the Third Party Tracking scores and audits.