The idea was to make it load long only once when it generates the thumbnails, as after generating it, there should be no reason to generate them again. However, the problem might be that loading thumbnails is still costly in terms of performance (loading and processing new image file, whatever its size).
Yeah I mean this is better than before as before for most people it'd never finish loading, but it still takes a really long time even on an i7-8700k to load a bunch of images. The delayed loading i implemented isn't the best user experience as it loads them in the main UI thread. I was curious if i can offload that to the background somehow, then it'd be perfect.