maybe I am missing something but isn't it barely faster than the offical ESP32_JPG? But fair enough, didn't know than JPEG decoding on MCUs is a widespread thing.
It's explained in a bit more details in this original blog post written before the library was optimised: https://atomic14.substack.com/p/the-fastest-esp32-jpeg-decod....
It's very easy to forget what a range of MCUs there are, from very puny, to very capable. For example the Espressif range of MCUs - which you'll find in all sorts of consumer products - are very powerful. Couple that with a lot of cheap SPI based display modules and you very quickly start wanting to show images.