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Document the impact of donation banner on Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS)
Closed, ResolvedPublic

Assigned To
Authored By
Peter
Jul 14 2021, 4:05 PM
Referenced Files
F34551784: layoutShift-2.jpg
Jul 15 2021, 6:21 AM
F34551779: layoutShift.jpg
Jul 15 2021, 6:21 AM
F34551781: largestContentfulPaint.jpg
Jul 15 2021, 6:21 AM
F34551786: largestContentfulPaint-2.jpg
Jul 15 2021, 6:21 AM
F34551050: wpt-1-firstView.png
Jul 14 2021, 4:05 PM

Description

Yesterday our alarms performance alerts fired because of increased Largest Contentful Paint (LCP) metrics. LCP is one of the Google Web Vitals that will impact SEO ranking. You can read more about how we measure the vitals https://wikitech.wikimedia.org/wiki/Performance/GoogleWebVitals

Largest Contentful Paint

When the banner is pushed the LCP increased in our tests from 1.264 s to 2.789s in our desktop tests.

The Largest Contentful Paint element has a red rectangle.

Before

largestContentfulPaint-2.jpg (1×2 px, 449 KB)

After

largestContentfulPaint.jpg (1×2 px, 431 KB)

Cumulative Layout Shift

When the banner is pushed the CLS increased from 0.01 to 0.18.

The element that shifted/moved are marked as red.

Before

layoutShift-2.jpg (1×2 px, 440 KB)

After

layoutShift.jpg (1×2 px, 447 KB)

Event Timeline

Peter renamed this task from Document the impact of donation banner on Largest Contentful Paint (LCP) to Document the impact of donation banner on Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS).Jul 15 2021, 6:21 AM
Peter triaged this task as Medium priority.
Peter updated the task description. (Show Details)