Just speculating here, but if you want to capture most of the energy of a star (e.g. by a Dyson swarm), this will be visible. And if you can only use a fraction of the energy available, this might reduce your expansion speeds.
Just speculating here, but if you want to capture most of the energy of a star (e.g. by a Dyson swarm), this will be visible. And if you can only use a fraction of the energy available, this might reduce your expansion speeds.