Then how would you conveniently open those files again with krita?
I mean, the idea would be to define a way to compress kra files more densely. Maybe enabling LZMA support in the zip loader. But usually with compression the actual compression is the slow part; decompression is generally a lot faster. So we’d care primarily about saving becoming very slow if we did that. So to avoid that, we can just save quickly and then save a second time, slowly, in the background.