Optimised

Tips, insights, and articles to help boost your website's performance.

Issue #18

June 11, 2021

Issue 18 - Bits & pieces

This week's issue is going to be a different from the usual format. Rather than focusing on one single topic, I'll be sharing a few web perf related news articles that have popped up over the last couple of weeks. It'll be a bit shorter than usual, but there'll be plenty of further reading for you to dive into!


Web Vitals. Core Web Vitals.

It's almost mid-June, and that means Google will soon start applying Core Web Vitals (CWV) to search rankings. Leading up to this, different teams at Google have put out some related updates.

An update for Cumulative Layout Shift (CLS)

Unlike other Web Vital metrics which are measured on page load, CLS is tracked over the entire duration of a page view. The new CLS calculation accumulates only the worst 'windows' of layout shifts regardless of the time spent on a page.

On top of this, CLS will now also have a higher weighting in Lighthouse performance scoring (bumping up from 5% to 15%). That being said, Google expects that most sites will see no change to their CLS scores.

There were also a few Web Vital related talks during the recent GoogleIO summit.

What's new in Web Vitals
This session goes through some of the changes Google's made to Web Vitals recently, including the aforementioned CLS update.

The business impact of Core Web Vitals
Here's a handy session for anyone trying to convince their manager, executives, or clients about the benefits that can come from focusing on Core Web Vitals.

Lighthouse 8.0 has been rolled out

Google's also started rolling out Lighthouse 8.0 across its performance measuring properties. Lighthouse is a set of audits that can be run against a web page to measure performance, accessibility, technical SEO and other best practices. It's available in the browser, as a Node/CLI tool, and is also integrated into many performance measuring services.

DebugBear has a handy rundown of everything new in the latest version. The highlights:

  • The CLS update metioned above is included in this update.
  • CLS now accounts of 15% of the total performance score.
  • There's handy filters that let you isolate audit results based on the Core Web Vital they impact.
  • A JavaScript treemap and code coverage report provides a visual way to assess where JS improvements can be made.

You can check out the tree map & filters by running a test on PageSpeed Insight.

WebP support is coming to WordPress

This is big. WordPress powers over 40% of websites. Being able to upload, and hopefully also convert images to WebP natively should be a huge improvement for a lot of sites. Here's the official announcement.


The next issue of Optimised will be in your inbox on June 25th. The website has an archive of all previous emails. It's a good place to recap on anything we've covered, and also handy to share with friends or colleagues.

As always if you've got any feedback or specific topics you want to be covered then just reply to this email.

Keep safe, stay well.
Fershad.

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