Performance Chat Summary: 19 September 2023

Meeting agenda here and the full chat log is available beginning here on Slack.
Announcements
- Welcome to our new members of #core-performance
- Hallway Hangout: Performance Improvements for WordPress 6.4 is scheduled for Thursday, October 19, 2023 at 04:00 PM GMT+1
- WordPress 6.4 beta 1 is September 27, 2023
- Mention of the WordPress Performance Team in the Search Engine Journal September 2023 article
Priority Projects
Server Response Time
Contributors: @joemcgill @spacedmonkey @aristath @swissspidy @thekt12 @mukesh27
- @spacedmonkey
- @mukesh27 I’ve been working on issue #22192 and have received some feedback related to backward compatibility on the PR. I’m now in need of feedback from Joe and Felix
- @thekt12 #58319 completed (about to be committed)
- @thekt12 #58196 in progress, planning to give for initial review tomorrow
- @joemcgill I made good progress on #57789 yesterday and could use a second set of eyes. It doesn’t full solve the issue of making Theme.json data persistent, but is a step in that direction, which reduces unnecessary recalculation of that data during a page load. I’m going to work on a parallel PR to the Gutenberg repo to get some testing of the strategy in the plugin prior to making the change in core.
Database Optimization
Contributors: @spacedmonkey @mukesh27
- @spacedmonkey
- Working on
- Needs review
- @spacedmonkey It is unclear of the path forward of #59188 there seems to be disagreement on best path forward
- @mukesh27 The majority of the work from my end has already been committed for the 6.4 milestone. I am now providing support to Jonny for the review and testing process.
JavaScript & CSS
Contributors: @mukesh27 @10upsimon @westonruter @spacedmonkey
- @spacedmonkey In need of review https://github.com/WordPress/wordpress-develop/pull/4824
- @westonruter Similarly, I have the elimination of manual script tag construction scope reduced to not include the admin. Now it is just the frontend and the login screen. PR ready for review. https://github.com/WordPress/wordpress-develop/pull/4773
Images
Contributors: @flixos90 @thekt12 @joemcgill @pereirinha @spacedmonkey
- @spacedmonkey Committed #58675
- @mukesh27 I worked on ticket #58894 and it was committed yesterday
- @mukesh27 Currently, I’m providing support to @pereirinha on ticket #58893
- @flixos90 Committed [56612] and [56613]
- @flixos90 Otherwise, reviewing the PRs for #58892 and #58893 which I see have received updates since, so I’ll take another look shortly after this chat
- @flixos90 One thing I’d like to get another round of review on is #58853 / https://github.com/WordPress/wordpress-develop/pull/4973
- @pereirinha I’m currently waiting for feedback on #58892 and #58893 I’m happy to support anyone in the last mile
Measurement
Contributors: @adamsilverstein @joemcgill @mukesh27 @swissspidy @flixos90
- @flixos90 Last week I spent some time conducting field analyses to assess the performance impact of the WordPress 6.3 release. Primarily focusing on Web Vitals metric LCP which measures load time performance, and how it’s affected both in general, but also specifically by the two major enhancements that were projected to affect LCP:
- the emoji loader script optimizations
- the lazy-loading plus fetchpriority improvements
- Sharing the most important highlights:
- Overall, the Largest Contentful Paint (LCP) passing rate has improved by 5.6% for classic theme sites and by 2.7% for block theme sites
- The Largest Contentful Paint (LCP) boost for classic theme sites using the emoji loader script is 3.4% to 7% higher than for those that don’t use it, and for block themes it’s 0.7% to 4.5% better as well
- When looking at only the sites where that is the case and which were still lazy-loading the LCP image with WordPress 6.2, the LCP performance impact amounts to a massive 16% to 21% improvement for mobile viewports and 6% to 9% on desktop.
- Lazy-loading accuracy has notably improved: In WordPress 6.3, only 9-10% of sites still lazy-load their LCP image for classic theme sites (down from 27-28% in 6.2) while for block theme sites it’s 5-8% (down from 17-29% in 6.2)
- @flixos90 drafted and published the Analyzing the Core Web Vitals performance impact of WordPress 6.3 in the field post
- @joemcgill Nothing new from me this week, but we expect to do an initial round of benchmarks against WP 6.4 beta1 after it’s released next week.
Ecosystem Tools
Contributors: @mukesh27 @swissspidy @westonruter
- No updates this week
Creating Standalone Plugins
Contributors: @flixos90 @mukesh27 @10upsimon
- No updates this week
Open Floor
- @joemcgill I wanted to mention that we should probably prepare some time after beta1 next week for some initial triage of any performance issues we see after the first round of code syncing from the Gutenberg project has occurred.
- @spacedmonkey I would like to start a tracking ticket for dev notes this team is going to work on
- Created https://github.com/WordPress/performance/issues/840 for tracking 6.4 Trac tickets that require dev notes
Our next chat will be held on Tuesday, September 26, 2023 at 15:00 UTC in the #core-performance channel in Slack.