I'm trying to implement impossible differential cryptanalysis on IDEA cipher based on the Miss in the Middle Attacks on IDEA and Khufu, I've started by implementing the cryptanalysis on 3.5-Round IDEA and in order to achieve this cryptanalysis I need an initial pair set of $2^{32}$ pairs.
I've written all the code from scratch and I've stumbled with the fact that this pair set is talking forever to generate using my code.
So what I need to know is if $1$ million pairs is taking $2$ minutes to be encrypted , is the execution time considered good or it need to be faster?