FOSS gamedev and creative worlds

If my calculations are right, generating a sphere that has a radius of 64 nodes would require somewhere between 2-3 mil operations. A sphere that big usually requires running the command 4-5 times, add to that, i never know when its done and needs to be run again except by looking at my FPS. I tried adding progress indicators but that only resulted in smaller portions of the sphere spawning each time i run the command.

How would one go about splitting up large operations? Ive thought of maybe seperating the functions from the actually node placing, but that would require first writing the changes to a multidimensional table, and then processing it. Though i have a feeling such large tables would segfault :-/

Maybe its possible to save the border of the sphere and then fill it in a register_on_globalstep function.