You may have already figured this out by now, but the main way to get a lot of waste is by using energy abilities. With 10K you can get a Worm B and start to make them back. That's still pretty slow, but it's doable.
I found that making sure to spend energy while doing other stuff worked out pretty well. You never reach a point where the game grinds to a halt due to lack of raw mana. But it's understandable if that feels kind of slow. I would guess that in future versions there will be other ways to get waste, because right now getting a Worm C is basically impossible.