Tad overkill, the Star Destroyer would have had enough firepower to destroy an old Constitution class starship.
The comparison is apples vs oranges though, the Federation was built for scientific discovery, the Empire for war and conquest, it's natural that they would have superior weaponry.
Although one does have to wonder how they would fare against the Borg once the Borg had lost a few dozen cubes and adapted to Imperial weaponry.
Then there's Q, who could turn Emperor Palpatine into a pot plant with a click of his fingers.
So, it's not quite as one sided if you think outside the Federation.
