Both in terms of game play, and CPU cycles. In this case, assume that overcharge doesn’t affect structures
For the former, purple/JUICE… I think Raynor would be a big culprit since his OCs would rain MULES like nobody’s business. Oh, ditto for Karax’ Shield Batteries. Everything else IIRC is on cd (so just time, no energy use).
For the latter, units would still be the bigger culprit for all of extra “bookkeeping” the game needs to, so it seems that should be fine?