If they wrote the program so that each individual quanta could only influence adjacent quanta then the fastest travelling information would be the size of the smallest quanta divided by the smallest time to calculate the influence. (Think sort of like conway's game of life)
In our universe that fastest travelling information is obviously the speed of light, so a quanta (we'll say that in our universe that's the planc length), influences another quanta every 10^-43 seconds (The planc time).
From this we can deduce that if we used this method, where information is communicated by adjacent sections. The processor can calculate everything about a single interaction with a frequency of10^31 Terrahertz, that's not a single calculation that's every single calculation about a single quanta.