It all depends on what the client is doing when it’s decoding, so YMMV, but progressive JPEG is not a panacea. In addition to the CPU concerns mentioned above t

It all depends on what the client is doing when it’s decoding, so YMMV, but progressive JPEG is not a panacea. In addition to the CPU concerns mentioned above there can be memory implications as well. Many progressive JPEG decoders require a full-sized destination buffer to decode. Baseline decoders usually only need one row of blocks. If most of the time some downsampling is required anyways, it can be done inline with baseline encoded images. A progressive implementation may need order n^2 memory footprint. If you have many pages with many images all of which are going to require some client side scaling this could add up to a lot of unnecessary alloc/dealloc too. But I encourage you to try both ways and pick a winner based on your own results.