When lazyloading iframes does (not) work (automatically)

WordPress has made some good progress to speed up site rendering the last couple of years and part of this is thanks to images and iframes having the “loading” attribute with value “lazy”, telling browsers these can be loaded later allowing other (more important) assets to take priority. Especially iframes can consume a lot of bandwidth (think embedded Google Maps or one or more YouTube videos), so the performance impact of lazyloading those can be very significant.

Unfortunately one cannot always rely on WordPress core to automatically make sure there is no performance penalty from stuffing your site with iframes. Here is a non-exhaustive list of when iframes will still delay your site:

  1. WordPress core does not always add the loading="lazy" attribute;
    1. if loading="eager" is set (which means load asap)
    2. if no width & height are set (as lazyloading iframes without those could cause layout shifts)
  2. Firefox (and some less important browsers) does not support lazyloading iframes even if loading="lazy" is set
  3. iframes in or near the “above the fold” part of a page are loaded immediately, even if loading="lazy" is set

Conclusion; show restraint when adding iframes; adding an image of Google Maps which links to (a separate page with) Google Maps is almost always as informative and the performance benefit of using an image instead of an GMaps iframe is huge. And when using iframes then consider using alternative solutions to avoid the performance impact (for YouTube you might want to give WP YouTube Lyte a try).

Want to know some Autoptimize secrets?

There’s a first for everything and so last week I did a presentation at a WordPress Meetup in Antwerp titled “Autoptimize: 5 secrets and an intermezzo” which at least I had fun with.

You can find a PDF export of the presentation here.

Questions go below, in the comments (or in the form on the contact page).

Mastodon oEmbed requests overload; use WP Rest Cache

Mastodon due to the decentralized nature can result in a significant extra load on your site if someone posts a link to it. Every Mastodon instance where the post is seen (which can be 1 but also 100 or 1000 or …) will request not only the page and sub-sequentially the oEmbed json object to be able to show a preview in Mastodon. The page requests should not an issue as you surely have page caching, but the oEmbed object lives behind /wp-json/ and as such is not cached by page caches. The solution; the WP Rest Cache plugin and one small code snippet (for now). A lot more info can be found in Donncha’s excellent post on the subject.

Autoptimize Pro released, secret discount code here ;-)

Autoptimize ProSo Autoptimize Pro has finally been released, somewhat secretively (I like flying under the radar).

All info about features can be found on https://autoptimize.com/pro/ including a 20% early birds discount code, but if you use my internet nickname/ handle of whatever you want to call it (it’s part of the domain of this blog and has 3 t’s in it 😉) as coupon code between now and November 16th, you’ll get an even bigger discount!

Be quick, your website will be too 😉

Autoptimize Pro is coming, 10 beta-testers needed!

It has been long overdue, but I’m finally almost ready to release Autoptimize Pro. The first version of AO Pro (an add-on to be installed on top off Autoptimize) will have Image optimization, CDN, fully automated critical CSS and a number of “boosters” to improve performance even more, with more features are in the backlog.

autoptimize pro boosters screenshot

If you’re interested in beta-testing fill out the form below and based on data submitted I’ll pick 10 beta-testers. As a beta-tester you’ll be able to use AO Pro free of charge until the end of the year.

Beta-testing is being finalized, I am currently not looking for additional testers.

Autoptimize 2.9 final beta, testers wanted!

I just upped Autoptimize 2.9 beta to version 4, which is likely to be the last version before the official 2.9 release (eta end June/ early July).
Main new features;

You can download the beta from Github (do disable 2.8.x before activating 2.9-beta-4) and you can log any issues/ bugs over at https://github.com/futtta/autoptimize/issues
Looking forward to your feedback!

Contact Form 7 alternatives

Contact Form 7: trouble right here in volcano city!Given the major change in Contact Form 7‘s frontend JavaScript and the problems having to optimize the JS or cache the page after the update, the question I get asked frequently is what alternatives there are to CF7.
So here is a very quick rundown of 3 such alternatives:

  1. Gravity Forms: premium-only, visual form builder, very flexible, big ecosystem (lots of 3rd party plugins & integrations)
  2. Formidable Forms: has a free Light version, drag & drop interface for building forms, very flexible (we currently use this on autoptimize.com), lots of integrations but smaller ecosystem.
  3. HTML Forms: free plugin from the team that also develops “Koko Analytics” (which I now use on all my sites) and “Mailchimp for WordPress” with a premium addon for extra features, similar to Contact Form 7, no frills, very light on JS so great for performance.

My advice; try HTML Forms if you have rather standard contactform-like forms and you’re not looking for something fancy (which CF7 is not either), try Formidable if you need drag & drop form building or if you (will) need more flexibility/ integrations.

Santa wrapping up Autoptimize 2.8!

I’m sure you have been good this year so Santa cannot but put a nice ribbon around the next version of Autoptimize, out later this month. These are the most important changes:

  • JavaScript: new option “defer but don’t aggregate” which *might* help with “total blocking time”
  • Images: add field to list images to be excluded from image optimization
  • Critical CSS: major improvements of the job processing mechanism, reducing time spent from up to 1 minute to just a couple of seconds.
  • Critical CSS: under “advanced options” replace “request limit” with “queue processing time limit” (default 30s).
  • Extra | Google Fonts: better parsing of version 2 Google Font URL’s (/css2/).
  • Misc. other minor fixes, see the GitHub commit log

In case you want to give Santa a hand with all that wrapping up, you can always download the Beta version here and take it out for a spin.

Autoptimize with support for AVIF images

You probably have heard about AVIF already, but if not; it is a new image format which is based on the AV1 video format and generally has superior compression than the better-known WebP, JPEG, PNG and GIF formats. Avif is currently supported by Chrome & Opera and can be enabled by setting the image.avif.enabled flag in Firefox.
So now you know what it is you may want to use it on your WordPress site? In that case -and the title kind of gives it away- the freshly released Autoptimize 2.7.8 now has support for AVIF if you have image optimization active. Just as for WebP Autoptimize hooks into the lazyload JavaScript to detect if your visitor’s browser supports AVIF and will switch the requests to the ShortPixel CDN to that format if so. If AVIF is not support but WebP is, the requests will be for WebP images and if those are not supported old-fashioned JPEG’s will be loaded.
So there you have it, AVIF is now available in WordPress!

Want to test AVIF images with Autoptimize’s Image Optimization?

So AVIF is a new(ish) image format that promises even better optimization then WebP and is supported in desktop Chrome & behind a preference in Firefox; go to about:config and set image.avif.enabled to true.
If you are using Autoptimize to optimize your images and you want to test AVIF images, you can use below code snippet to do so;

add_filter('autoptimize_filter_imgopt_webp_js', function(){return '<script data-noptimize="1">function c_img(a,b){src="avif"==b?"data:image/avif;base64,AAAAIGZ0eXBhdmlmAAAAAGF2aWZtaWYxbWlhZk1BMUIAAADybWV0YQAAAAAAAAAoaGRscgAAAAAAAAAAcGljdAAAAAAAAAAAAAAAAGxpYmF2aWYAAAAADnBpdG0AAAAAAAEAAAAeaWxvYwAAAABEAAABAAEAAAABAAABGgAAABoAAAAoaWluZgAAAAAAAQAAABppbmZlAgAAAAABAABhdjAxQ29sb3IAAAAAamlwcnAAAABLaXBjbwAAABRpc3BlAAAAAAAAAAEAAAABAAAAEHBpeGkAAAAAAwgICAAAAAxhdjFDgQ0MAAAAABNjb2xybmNseAACAAIAAYAAAAAXaXBtYQAAAAAAAAABAAEEAQKDBAAAACJtZGF0EgAKCBgADsgQEAwgMgwf8AAAWAAAAACvJ+o=":"data:image/webp;base64,UklGRhoAAABXRUJQVlA4TA0AAAAvAAAAEAcQERGIiP4HAA==";var c=new Image;c.onload=function(){var d=0<c.width&&0<c.height;a(d,b)},c.onerror=function(){a(!1,b)},c.src=src}function s_img(a,b){w=window,"avif"==b?!1==a?c_img(s_img,"webp"):w.ngImg="avif":!1==a?w.ngImg=!1:w.ngImg="webp"}c_img(s_img,"avif");document.addEventListener("lazybeforeunveil",function({target:a}){window.ngImg&&["data-src","data-srcset"].forEach(function(b){attr=a.getAttribute(b),null!==attr&&-1==attr.indexOf("/client/to_")&&a.setAttribute(b,attr.replace(/\/client\//,"/client/to_"+window.ngImg+","))})});</script>';});

Use the the code snippets plugin to add this (easy and safe) or if you’re adventurous add it to your theme’s functions.php.