Web Performance News, December 2019

Photo by Jeremy McKnight on Unsplash

The festive season is on its way, so, to save you from boredom while away from a keyboard, we are sending you a December edition of our Web Performance Newsletter.

Important update — to not miss a new edition of this newsletter you can now subscribe to it. We are planning to send a new one every month or two.

We don’t have much experience with newsletters and your feedback is very important for us. If you have any suggestion or found a typo, please drop me a line at dmitry.pokidov@pixboost.com.

And here we go!

• @simonhearne wrote his #webperf prediction for 2020: https://simonhearne.com/2019/2020-predictions/. Definitely, have a look, there are some surprises there! I could only guess Web Assembly :)
• @stoyanstefanov published 2019 Web Performance Calendar again! I would like to recommend to read each and every post from it, including previous years — https://calendar.perfplanet.com/2019/. My favourite is about images, of course — https://calendar.perfplanet.com/2019/the-ugly-truth-about-optimising-beautiful-images/.
• Instagram Engineer @mr_sharpoblunto wrote a series of posts about making instagram.com faster: Part 1, Part 2, Part 3, Part 4.
• HTTPArchive published the 2019 edition of their Web Alamanac. They tested 5.8 millions of websites and collected all the facts about them. For instance, did you know that almost half of the requests are still using HTTP/1.1?

Some industry news that we found important:

• This one is a biggie — Safari now supports Intersection Observer! Intersection Observer is a relatively new Web API for lazy loading content on the page. At Pixboost we are using it in our pixboost.js and pixboost-react libraries. My biggest problem with Intersection Observer was a polyfill that is quite buggy and most of the time we preferred to not use lazy loading at all if Intersection Observer was not available on the browser.

• Safari has just implemented Intersection Observer API, but there is a new version of spec coming: https://developers.google.com/web/updates/2019/02/intersectionobserver-v2. The latest version is not a full rewrite, but adding some additional functionality to better track visibility of the elements.
• Chrome is implementing a change to calculate image dimensions before loading it so that page layout won’t be affected. Worth to mention that Firefox already has this upgrade. To be ready just add width and height attributes to your <img> and <video> elements. Google Group discussion and explanation from @jensimmons:
• In case you missed it, Google is using page speed as a ranking factor on the mobile search since 2018. Here is a quick summary of how that decision influenced the Web so far.