OP, have you tried loading="lazy" ? I don't know if it works with the picture tag but it is worth trying I think.
Very often, webpages contain many images that contribute to data-usage and how fast a page can load. Most of those images are off-screen (non-critical), requiring user interaction (an example being scroll) in order to view them.
The loading attribute on an <img> element (or the loading attribute on an <iframe>) can be used to instruct the browser to defer loading of images/iframes that are off-screen until the user scrolls near them.
For those on mobile and can't right click
<source srcset="https://static.hansenzhang.com/travel/places/2019-07-04-nort... type="image/webp">
<source srcset="https://static.hansenzhang.com/travel/places/2019-07-04-nort... type="image/jpeg">
<img src="https://static.hansenzhang.com/travel/places/2019-07-04-nort... alt="travel/places/2019-07-04-northcarolina-3-color.jpeg">
I was curious about the picture tag. Here is what Mozilla documentation says https://developer.mozilla.org/en-US/docs/Web/HTML/Element/pi... :
The HTML <picture> element contains zero or more <source> elements and one <img> element to offer alternative versions of an image for different display/device scenarios.
The browser will consider each child <source> element and choose the best match among them. If no matches are found—or the browser doesn't support the <picture> element—the URL of the <img> element's src attribute is selected. The selected image is then presented in the space occupied by the <img> element.
To decide which URL to load, the user agent examines each <source>'s srcset, media, and type attributes to select a compatible image that best matches the current layout and capabilities of the display device.
The <img> element serves two purposes:
It describes the size and other attributes of the image and its presentation.
It provides a fallback in case none of the offered <source> elements are able to provide a usable image.
Common use cases for <picture>:
Art direction. Cropping or modifying images for different media conditions (for example, loading a simpler version of an image which has too many details, on smaller displays).
Offering alternative image formats, for cases where certain formats are not supported.
Saving bandwidth and speeding page load times by loading the most appropriate image for the viewer's display.
If providing higher-density versions of an image for high-DPI (Retina) display, use srcset on the <img> element instead. This lets browsers opt for lower-density versions in data-saving modes, and you don't have to write explicit media conditions.
The resolution scaling is a good idea as well. I used the picture tag initially as a fallback for browsers that don't support webp images. More importantly I need to actually create scaled images which I have been putting off...
Thanks for your comments/advice!