Lazy-loading can be implemented sloppily, but browser-native lazy loading is now good enough to be considered optimal.

The problem is that Google Page Speed dings you for not having lazy loading, and people add crappy JavaScript lazy loading that satisfies Google, but makes the user experience worse.

WebP is good iff it improves rendering times (which it does). That's not google's fault really.

The problem has been, until recently, Safari didn't support WebP, so you had to implement a fallback to jpg. More complicated HTML, more images to compress and manage, all for a very marginal improvement.

its look at any site in chrome dev tools.

I assume that those sites will vanish quickly though.

"Lazy loading" interactive content is an entirely different thing.

Shopping pages with tons of product images, Infinite scroll (yuck) are different...

That's at least with the HTML5 async image standard in Firefox. It's up to the browser after all, so if yours loads images too slow the issue might be there. And sure, if the images are huge they will take a long time to load, but that's also covered by the core web vitals.

A site I built a while ago is a good test case for that imho, https://www.sustaphones.com/. Long list, many small images, loaded from a CDN. I can maybe provoke a flicker with the scrollbar, but not with regular scrolling.

Edit: That's for broadband. With a 56K modem or something that's of course a different story. But loading a bunch of images in advance on the modern web is also not a good option then.

Your test case is totally meaningless, the images are under 3kb. Full (non-lazy) image loading is far more important on websites with lots of large images.

You can always construct a theoretical case where it does not work great. But on those pages and connections loading all the images in advance will usually also lead to a bad experience.

It depends though on the content page and on how slow the network is exactly, doesn't it? I often enough preferred to have the text already and decide based on that whether to wait for the images. Async with non-jumping base content (which the core web vitals also cover) is great for that.

And with it being a browser feature, even if Google pushes for it the user can always deactivate it. On real browsers at least.

Native lazy loading is broadly supported, it works well, has no overhead, and you can override the behaviour if you always want eager loading.

There's no point in complaining about it that I am able to grasp.

I don't have data on this but I assume that JS lazy loading is dying rapidly because this is not a critical feature that must polyfilled for legacy browsers.

Of course, plenty of sites will keep their JS lazy loading cruft until the next code refactoring / optimization.

But I am very happy that native lazy loading has been standardized and implemented.

I was critical at first as well. But I tested it on the site I linked and on other sites with bigger images, and it just worked that well that I stand to what I said. This feature is a net-positive and in most scenarios the loading will either not be noticeable, or it will be an advantage overall.

He preferred to wait all the time until images are loaded to start reading articles, with a flaky slow connection, or to try start reading while parts of the site still load? Especially on a slow connection not having to load the images immediately, or at all if the visitor does not scroll down as much, can make browsing so much better.

The main problem the customer I was referring to had is that the user interfaces for these websites would not function until they finished loading after 30 to 90 seconds, despite the fact that the user interfaces rarely changed. These were for cloud based accounting and scheduling platforms the business was required to use.

Developers really should have to try to use the systems they build on systems that have low bandwidth / high latency network connections rather than the typical fibre fed office environment. If you can build a website that works well for that use case, it's probably going to be incredibly snappy on a fast connection. Judging by how bloated the web is these days, that is rarely the case in today's world.

My definition of broadband is correct, and 1.8Mbps does not match it. Where I live 1.8Mbps just is not legal broadband. In the US that also does not count as broadband anymore, see https://broadbandnow.com/report/fcc-broadband-definition/, and it hasn't for over a decade.

I must say that the FCC really messed up by redefining broadband when they were the ones that had originally defined it in terms of RF spectrum usage. Here in Canada, the telecom regulatory body set the Basic Service Objective to be 50 Mbps download and 10 Mbps upload. They didn't try to redefine what broadband is and overload a term that already had meaning in the telecommunications space.

Personally I think latency is more important with modern internet connections. 10 Mbps is still quite usable for a lot of things, but not if it's 500ms RTT via a satellite. Sadly most telecom regulators ignore latency.

The typical WordPress lazy loading script doesn't start loading the image until it is scrolling into view. Try a typical food blog, scroll moderately slowly and you'll still get to see every single image load.

edit: your example works great, but is in outlier in the implementation, and benefits from tiny images that load quickly.

My background that made me write the comment above is that I implemented lazy loading for a feedreader in JS, with predictive early loading to exactly avoid this problem, and I did test the browser feature just recently again. In those scenarios lazy loading really does work well enough for my statement to be true, according to my testing. For common connection speeds and image sizes only of course. Though I'd argue it also helps in less optimal scenarios exactly because it somewhat decouples the image loading from the page load - that that overall experience was horrible on long threads with many images in the feedreader was why the lazy loading feature was added, the contrast was stark.

I should have defined that better in the comment above and given your experience more validity. Next time :)

This is an example of what I am talking about.

https://clayimports.com/collections/colors

It "passes" the google lazy load audit, but is a terrible user experience. Doing no image load optimization would be much better than what they are doing presumably to please google.