That seems like a lot of extra space for one player, although there are the other setup layers and masks too. Photoshop just makes really big files. I don’t know why that file is that large. However, I think it just is what it is.
I can add it to the list to look into saving PSBs in a future release. Getting PS to save files through the new scripting API is a major pain so I can’t promise anything. Adobe still hasn’t provided any good documentation for saving image files either so a lot of things to get it to accept the save settings correctly is trial and error. Nothing about this new API has been fun the last 2 years because the API engine is still only half built. There are still missing parts and almost no documentation.