It would be nice if we could export our maps into a single image file so that we could minimize lag
You can do exactly that.
Edit your map then click the button showing an arrow pointing down in the top left corner of the layers menu:
That will export your map to a JPG or a PNG file for you.
What would be really nice would be if it could export it into some kind of container file that would include the map flattened AND split into segments that, and that Astral could read back in, as a single file, giving you the whole map but allowing Astral to treat it like a segmented map for “lag reduction”.
I definitely think Astral should have a built in way to slice up maps. Kinda annoying that I have to import a map into a tool I can slice images into 5+ pieces and then upload each separate to minimize lag.