We often measure the performance of websites at a fixed and finalised state. What about the in-betweens and interstitial states? They too contribute to the journey our users are on.
How fast and smooth is navigating between pages? How do the loading states feel and look? Just because interacting with those cases often lasts split seconds (or, at least *it should*) doesn’t mean they are not worthy optimising. They all contribute to a holistic experience.
All experiences should be fast, no matter how temporary they are.
Karolina
#### What’s Performance newsletter?
Performance Newsletter is a fortnightly mailing by [Calibre](https://calibreapp.com), featuring web performance tools, talks and resources.
Don’t worry—we don’t spam. If you’d like to leave, [unsubscribe]() at any time. Suggest content [here](mailto:[email protected]).
Slow and jarring experiences when navigating sites are not uncommon. Learn how bfcache affects perceived performance, how to measure and improve it.
### [Progressively delivering new image formats with CSS and Cloudflare Workers](https://jross.me/progressively-delivering-new-image-formats-with-css-and-cloudflare-workers/)
[James Ross](https://twitter.com/CherryJimbo)
Images can have a negative impact on speed. Know how to reliably serve new image formats using Cloudflare Workers.
# Case Studies
### [Web performance case study: Wikipedia page previews](https://techblog.wikimedia.org/2020/11/23/web-performance-case-study-wikipedia-page-previews/)
[Noam Rosenthal](https://twitter.com/nomsternom)
Find out how the Wikimedia Performance Team evaluated speed issues with a preview popup and what to avoid if you’re working on similar interface patterns. Bonus anteater included.
# Tools
### [Responsive Video Poster](https://nigelotoole.github.io/responsive-video-poster/)
[Nigel O Toole](https://www.purestructure.com/)
Gain creative control over placeholder images for videos and improve their performance with this handy JavaScript library.
# Talks & Podcasts
### [This Is Your LCP On Images](https://www.youtube.com/watch?v=YMqnPeZHcuc&feature=youtu.be&ab_channel=HenriHelvetica)
[Patrick Hulce](https://twitter.com/patrickhulce)
Get the hang of how images affect your Largest Contentful Paint metric readings. Advice by Lighthouse core contributor.
### [Life of a Pixel](https://www.youtube.com/watch?v=PwYxv-43iM4&t=82s&ab_channel=BlinkOn)
[Philip Rogers](https://github.com/progers)
Let me tell you that pixels go on quite a journey before they reach our eyes. Learn all the nitty-gritty details of how Chrome turns content into pixels.
This email is brought to you by the team at [Calibre](https://calibreapp.com). Our performance monitoring platform helps you deliver stellar user experiences to everyone.
Performance Newsletter is sent from the traditional lands of the Wurundjeri people of the Kulin nation. We acknowledge that sovereignty was never ceded and pay respects to the Elders past, present and emerging.
