ShortPixel Adaptive Images vs. Autoptimize's "Optimize images" option
Which one should I use? ShortPixel Adaptive Images(SPAI) or Autoptimize's "Optimize images on the fly and serve them from a CDN" option?
Both use the same ShortPixel service, the ShortPixel Adaptive Images API and both can deliver "next-gen" images (e.g. WebP), but there are differences.
Autoptimize uses a combination of a server- and client-based approach: for image optimization the image URLs are changed server-side with the CDN url, but client-side logic is only implemented if lazy-loading and/ or WebP delivery are active.
ShortPixel Adaptive Images tries to determine in the browser what is the image's resolution for that particular device resulting in better sized images in most cases, but for this purpose it has to lazy-load the images which could cause incompatibilities with some plugins and themes (here's how you can troubleshoot that)
Our advice is to try ShortPixel Adaptive Images if you don't have Autoptimize yet and if you see any incompatibility to install Autoptimize and use the image optimization in there. If you have Autoptimize already you can start with that, but if you want perfectly sized images for each device being requested try out Shortpixel Adaptive Images (deactivating image optimization in Autoptimize).