Don't know about the other links you've posted, but for photocraft the vast majority of those issues are from the engine that process the image itself, not about the GUI. In fact, as far as I can tell, none of the artcraft apps are that complex in terms of GUI to be slow down by any choice of GUI framework really. There could be performance differences between them, yes, but not so much.

With vectorcraft loading shape libraries can be slow, but this is a background thread.

egui was a great choice given the results; also egui's wasm support is very good, which means artcraft supports wasm; i.e. they can run on a browser.