.1J/GH (or .1W/GH) comes out to 100J/TH. So 42J/TH would make it roughly 138% more efficient?
As a point of reference, the Joule is a measure of total energy per-second so 1 Joule = a 1 Watt load averaged over one second.
A Watt is a measure of energy at any given instant in time.
A fun example: One of our lasers produces an average of 100W of power firing 100J pulses that are 1ns wide (0.000,000,001sec) at a rate of 1 shot per-second: peak power of those 1ns wide pulses = 100,000,000,000W or 100Giga-watts.