Oh, then if you don’t need to export them as the “spaced apart” layout as-is, you can use the crop tool to specify a region to export. That way it shouldn’t crash. If you draw those images on different layers apart, each layer won’t be as big so you can succesfully save it.
The recent project I’ve been doing is sized at 10641x7730 and it works without any particular problem :D
Also in v0.3 there will going to be a layer moving feature so you can move individual pictures around granted you’ve painted them in separated layers.