It was a dark day on the powerscaling forums for star wars fans, the day "200 gigatons per shot" died.
weirdly enough, the firepower displayed in the final clip by the 3 venators in the clone wars is actually respectable, destroying kamino in short order.
and also live-action isn't any better. the first-order siege dreadnought, a 7-kilometer long super-ship (ISDs are only 1.6), with 2 gigantic cannons made blasts maybe on par with modern nuclear weapons.