[nextaccountic]

it's a throughput thing yes, or in my case it's also a desire to not hog the cpu with bulk image processing

features like progressive jpegs and some color spaces aren't supported. I think it could be but it isn't and not sure why

jpegs found in the wild will typically not make use of hardware acceleration or use just it for a subset of the decoding (not sure about the details). browsers didn't bother using hardware acceleration for jpegs just for the images that can be processed fine

so it is meant for jpegs you control rather than jpegs you find on the web. unless you convert them yourself