Scientific American figures it out:
According to an old Cosmic Variance post, the power of one of the LHC's proton beams at full energy is 10 trillion watts (TW). (A watt is a joule of energy per second.) A household microwave produces 500 to 1000 watts of power. Let's call it 700 watts. And defrosting a frozen pizza takes about six minutes*. So that's 700 joules/sec x 360 sec = 252,000 joules of energy needed to defrost a pizza
Therefore: 252,000 joules / 10^13 joules per second = 3x10^-8 second for the LHC to defrost a pizza
That's 30 nanoseconds (billionths of a second).
I've always hated thawing my frozen pizzas.