When you start an engine smoke is released from the aircraft wiring harness through the smoke bleed valve and out the exhaust pipe. It takes a while to generate more smoke to replenish the wiring supply. It takes electrical energy to produce, thus the higher load. The smoke is necessary. In the event of a wire breach, it is released in the form of " does that smell like electrical wiring to you?" It's like the canary in the coal mine. In the old days, before capton wiring, the Lucas electrical company sold supplemental smoke for refilling wiring in British cars. I know it sounds very strange so I'm surprised your instructor pilots never explained this to you.
