Just out of curiosity, why did the software not always use the 'fast path'?
Benchmarks are meant to be reproducible, meaning perfectly predictable. CPUs have things called branch predictors which try to predict what the software is going to do and try to do the calculation ahead of time resulting in (hopefully, if it predicted right) faster execution time. If you know which 'branches' a benchmark goes down, you can make a program which can coax the branch predictor to always make the right guesses for a given benchmark.
A program branches whenever you encounter some sort of conditional if-else statement.
Print '2' is lot less operations than (insert formula here) if you know the answer is already 2.