Issue #25—The real impact of image optimisation, gain speed with variable fonts, accessibility for everyone and more.

        17 June 2019

#### PerformanceNewsletter

#### Issue 25

#### Editor’s Note

We’re working hard to release a few major features to Calibre, one of them being **Insights**—a weekly or monthly email report providing a summary of what’s changed in your site’s performance. Insights is going to be instrumental in being up-to-date on how speed fluctuates over time.

Thank you to everyone who shared article recommendations to be featured in the newsletter—quite a few of them were added to our backlog ✌🏻**Keep them coming!**

We’re still **looking for your performance questions to feature in the Q&A section**—whatever you’d like to know about performance, let us know! The answer will be featured in the upcoming Performance Newsletter issue.
— Karolina

#### article

## Set performance budgets with Lighthouse

Performance budgets are crucial to monitoring speed regressions and ensuring they can be addressed swiftly. In her article, [Ire Aderinokun](https://twitter.com/ireaderinokun) explains how to set up budgets with Google Lighthouse and use them with the command-line interface.

[Your first performance budget with Lighthouse →](https://bitsofco.de/your-first-performance-budget-with-lighthouse/)

#### Book

## Build with accessibility at the forefront

Accessibility can often be an afterthought (similarly to performance) making the Web not only less pleasant to use but also out of reach to some. In her book, [Laura Kalbag](https://twitter.com/laurakalbag) thoroughly explains accessibility strategies that should be implemented to make the platform inclusive of all.

[Accessibility for everyone →](https://abookapart.com/products/accessibility-for-everyone)

#### article

## Use variable fonts to enhance performance

Variable fonts enable us to use a single file to represent multiple font weights, lowering the number of requests and speeding up overall performance. [Matt Ström](https://twitter.com/ilikescience) explains what can we gain by using them today.

[Switching to variable fonts →](https://matthewstrom.com/writing/variable-fonts/)

#### article

## Is image optimisation really worth it?

An excellent study from Uploadcare detailing how Alexa Top 500 websites stack up in terms of performance. Focusing on the imagery, we can see predictions on how appropriate handling of images could improve page views, conversions and overall UX.

[Image Optimization: Understanding the Exact Impact on Google’s Performance Score to Rank Higher in 2019 →](https://blog.uploadcare.com/image-optimization-and-performance-score-23516ebdd31d)

#### article

## Learn how to improve render times with critical CSS

Inlining critical CSS to render above the fold content as fast as possible can drastically speed up rendering, even on mobile devices. [Milica Mihajlija](https://twitter.com/bibydigital) explains what tools to use to implement your critical CSS strategy.

[Extract critical CSS →](https://web.dev/extract-critical-css)

#### new in calibre

## What Calibre released last month

📚[**Release Notes: May**](https://calibreapp.com/blog/release-notes-may-2019/)

Here’s our monthly roundup of what was released in May: **Calibre Insights** preview—an email digest in the form of a summary of your sites current performance, direct input for budgets, toggling Test Profiles on charts and more.

🔐[**Validate the security of webhooks**](https://calibreapp.com/docs/api/webhook-security)

#### Spread the word about perf.email

We’d love to see more people reading
                              [perf.email](https://perf.email/); if you’d like to help—forward this email to a friend, tweet, or shout from a rooftop.
                                It goes a long way. ✌🏻

#### Brought to you by

                              ♠ [Calibre](https://calibreapp.com/). Make the web fast for everyone.

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                Issue #26—How does Google PageSpeed work and affect SEO rankings, the cost of JavaScript in 2019, find a cost of adding an npm package and more.

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                Issue #24—Webfont loading in Google Fonts, Lighthouse 5.0.0 and zero parse and compile for JavaScript.