thumbhash VS lazysizes

You may wish to investigate cloudflare's image API: https://developers.cloudflare.com/images/cloudflare-images/

If the reason you were unable to use a CDN cache was because your access patterns require a lot of varying end serializations (due to things like image manipulation, resizing, cropping, watermarking, etc.), then this API could be a huge money saver for you. It was for me.

OTOH if the cost was because compute isn't free and the corresponding cloudflare worker compute cost is too much, then yeah, that's a tough one... I don't have a packaged answer for you, but I would investigate something like ThumbHash: https://evanw.github.io/thumbhash/ - my intuition is that you can probably serve some highly optimized/interlaced/"hashed" placeholder. The advantage of thumbhash here could be that you can optimize the access pattern to be less spendy by simply storing all of your hashes in an optimized way, since they will be extremely small, like small enough to be included in an index for index-only scans ("covering indexes").

note: I haven't had time but I would live to investigate into keeping tiny thumbnails hashes in my db as mentioned in https://evanw.github.io/thumbhash/

Check the script here: https://github.com/evanw/thumbhash/blob/main/examples/browser/index.html

While it's similar to BlurHash, the color performance is much better for the same filesize. Here's a a demonstration of this from the demo page (with ThumbHash in the middle and BlurHash on the right):

Webp took a long time to get some broader adoption but it fulfills the roll of jpeg: a decent enough quality looking picture but at a reduced file size. However, it is based on the VP8 video codec. So in other words, you can think of it as a still frame of a VP8 video. This has some disadvantages because it can only load the image line by line from top to bottom (as opposed to a kind of blurry but progressively improving picture like a slow loading jpeg). So this leads to tricks like storing a very small thumbnails version and loading the actual original image. But tricks are tricks, and they're a bit annoying to deal with. For a very advanced version of this "store a small version and load that first" check this out https://evanw.github.io/thumbhash/ (it creates a blur that has the the appearance of the photo that's loading but it can do it within bytes of data).

Use a JavaScript library to implement lazy loading. There are a number of JavaScript libraries available that can help you implement lazy loading, such as Lazysizes and Lozad.

Normally I would write some client-side JS to do this but as this project is solely server-rendered I opted to use a simple tried-and-true library for this: lazysizes.

I recently did some optimizations on my personal website to make the images load “lazily.” In other words it only loads stuff once it hits the viewport. I think that’s what you’re looking for. I tried two techniques:

1. There is an HTML attribute to do just this and it seems to work for iframes too: https://developer.mozilla.org/en-US/docs/Web/Performance/Laz...

2. There is a simple library called “lazy sizes” (https://github.com/aFarkas/lazysizes)

I tried to avoid the lib and use the native HTML… but for whatever reason the lib worked more reliably/effectively in manual tests as well as in my benchmarking via PageSpeed / Lighthouse. YMMV!

lazysizes is better than loading="lazy"

Since browsers support native lazy-loading, do we need libraries like this https://github.com/aFarkas/lazysizes?

Use Lazy loading for below-the-fold images. (You can use different 3rd party libraries like Unveil, lazysizes, etc.)

⚡️ Lazy load images with lazysizes

You can also use this really great library for handling the loading of images in a holistic and well-supported way or you can look at manually implementing the LQIP technique.

And, lazyloading is only for images. If you use e.g. lazysizes you can do anything with it. I'm a digital publisher so I use it for ads and embedded tweets/IGs and so on.