JPEG XL: faster loading with progressive display

[corr]

In fullscreen JPEG images that are not cached are first displayed in a lower resolution version (progressive) until it is completely loaded. Would something like this also be possible to implement for JPEG XL? There you have to wait much longer until the image is displayed.

I wonder what could be the reason why it takes about a second for images (>=4000px). CPU, RAM and SSD are hardly used to capacity when opening.

[xmozg]

The developers stated that jpeg xl will open as fast as jpeg. But in xnview it opens several times slower and also the fps is reduced: viewtopic.php?f=62&t=45830

[xmozg]

I just tested opening my big image in irfan view: jpeg xl opened ~1.5 times slower than jpeg. In xnview jpeg xl opened ~4 times slower than jpeg! This is terrible, Pierre should do something about it.