Overheating: A problem everywhere. The logistics of a post-scarcity society may have eliminated most material-supply problems; advanced ergtech may have made energy not a meaningful practical constraint; computer power may be an absolute bargain everywhere; but even with every fancy high-tech possibility up to and including neutrino-catalyzed cooling in play, the requirement for heat dissipation still enforces speed constraints on nanotechnology, density limits on computronium, causes problems for guns firing on full-auto, prevents stealth in space, and requires most heavy industry to be kept at least in orbit even if its customers are downwell. Damn you, thermodynamics!
Cut the Juice: While a minor thing, usually harder to do than it seems; UPSes are a standard computer component in much of the Worlds, and various polities, the Empire included, build heavily decentralized power grids because they’ve seen this one in action before, thanks.
Besides, coming from the school of sensible engineering design, there are switches for this sort of thing.
Abusing the Kardashev Scale For Fun and Profit: Working their way up to this right now, the Empire has a couple of Dyson spheres, one under construction, the other completely dedicated to energy generation, plus other energy-generation facilities scattered here and there and about the place. This makes them, I believe, a solid Type II, although given the constraints of light speed, it’s going to take them a while to work up to III.