Switching-on/off 1000V * 1000A in 10ns
I can't be arsed to look up the actual switching time of a real device, but the current and voltage spells IGBT to me:
http://en.wikipedia.org/wiki/Insulated-gate_bipolar_transistor

I know IGBTs are used for high power converters in places like windturbines and slow switching there would mean too high switching losses.