- [x] (6332) The IntersectionObserver method of lazy-loading loads cached images visibly late on slower devices. Previously, it was also showing the "broken image" icon briefly, which we mended by placing a dummy transparent image as the initial src.
- Reverted that ugly transparent image fix.
- Use the browser's built-in `loading="lazy"` instead. Sorry, Safari.
- [x] Size-optimization did not take "device pixel ratio" into account.
- When resizing an image through the CDN, we can't just take the dimensions of the tag in pixels directly -- we need to take zooming into account, otherwise the image ends up blurry.
- Previously, we quickly disabled optimization for the channel avatar in the Channel Page because of this. Now that we know the root-cause, the change was reverted and we now go through the CDN with appropriate sizes. This also improves our Web Vital scores.
- [x] Size-optimization wasn't really implemented for all ChannelThumbnail instances.
- The CDN-optimized size was hardcoded to the largest instance, so small images like sidebar thumbnails are still loading images that are unnecessarily larger.
- There's a little-bit of hardcoding of values from CSS here, but I think it's a ok compromise (not something we change often). It also doesn't need to be exact -- the "device pixel ratio" calculate will ensure it's slightly larger than what we need.
- [x] Set `width` and `height` of `<img>` to improve CLS.
- Addresses Ligthhouse complaints, although technically the shifting was addressed at the `ClaimPreviewTile` level (sub-container dimensions are well defined).
- Notes: the values don't need to be the final CSS-adjusted sizes. It just needs to be in the right aspect ratio to help the browser pre-allocate space to avoid shifts.
- [x] Add option to disable lazy-load Channel Thumbnails
- The guidelines mentioned that items that are already in the viewport should not enable `loading="lazy"`.
- We have a few areas where it doesn't make sense to lazy-load (e.g. thumbnail in Header, channel selector dropdown, publish preview, etc.).
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