There is one thing that I hadn’t read there about Cell’s speed and balancing :
Maybe you can make ressources collected have some weigh that can slow cells when they got too much.
I don’t really have any value but to me it seems plausible and there would be different strategies that can be planned about ressource gestion and cells interactivity :
Either you are well defended and can stock ressources while being slow, or you can be fast and aggressive to make your ressources relieve on your preys.