Oh, and here's
an interesting site I found not too long ago.
except that star wars ships dont show their power by far
in the actual damage they produce.
for example the slave one's main gun power output is no way near
the 2kt/shot they claim on that site
(at around 1:33) the slave one hits a small rock and it bursts apart.
that impact is no 2 kilotons of energy deposited in that rock.
a ton or two maybe, comparing with modern day mining activities.
same thing for AT-AT's for example, which would have a similar main cannon per-shot output, if not more, and they hit like modern day artillery shells.
if they had those kiloton outputs the site is proclaiming the battle of hoth would have been a nuclear wasteland.
its the same situation for big ships, based on the effects that hits have on hull material, those shots cannot have gigaton impact energies.
as there were lots of situations where simple kinetic impact created huge damage, which is far far far away from being gigaton ranged.
if those cannons had gigaton shots, the ships would poof like tissue paper.