Optimization: Passive listeners and scrolling performance

[rfultz]

Background

Looking to optimize the site's performance and that of the homepage specifically, the Lighthouse tool in Chromium browsers has made some suggestions. Some of these will have repercussions throughout the app so we're going to make them their own tickets.

Recommendation: Does not use passive listeners to improve scrolling performance

Consider marking your touch and wheel event listeners as passive to improve your page's scroll performance. details

Overview

We could add , {passive: true} to the scroll listeners.

Benefit (the 80 of 80/20)

It's recommended but not sure know who might notice

Effort (the 20 of 80/20)

Minimal

Complications

• Being that these are third-party code (e.g. recaptcha), we may not be able to do this (like if the listeners are automatic and the code doesn't give us an option for passive)
• Would just need to check that recaptcha and other scroll-listeners still work

Related tickets

• Preload key requests
• Remove unused JavaScript
• Remove unused CSS
• Preconnect to required origins
• Eliminate render-blocking resources
• Ensure text remains visible during webfont load
• Reduce the impact of third-party code
• Image elements do not have explicit width and height
• Serve static assets with an efficient cache policy
• Minimize main-thread work
• Avoid an excessive DOM size
• Reduce JavaScript execution time
• Avoid enormous network payloads
• [aria-hidden="true"] elements contain focusable descendents
• Elements with an ARIA [role] that require children to contain a specific [role] are missing some or all of those required children
• [aria-*] attributes do not have valid values
• ARIA IDs are not unique
• Lists do not contain only
• elements and script supporting elements (<script> and )
• [user-scalable="no"] is used in the element or the [maximum-scale] attribute is less than 5
• Links to cross-origin destinations are unsafe
• Serves images with low resolution