Optimization: Minimize main-thread work

[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: Minimize main-thread work

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. details

Overview

Could save six seconds of our load time, may be satisfied by some of the other optimization tickets (especially pruning unused code), but may be a significant effort

Benefit (the 80 of 80/20)

Minimal to moderate?

Effort (the 20 of 80/20)

Potentially significant

Complications

With so many possibilities, I could see this becoming multiple other tickets

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
• Does not use passive listeners to improve scrolling performance
• Image elements do not have explicit width and height
• Serve static assets with an efficient cache policy
• 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