I am trying to efficiently use multicores for my fizzbuzz https://github.com/mlitchard/swiftfizz project. My fizzbuzz uses a Fibonacci generator as input, and this is where it can get computationally heavy. I believe I have picked the best algorithm for my project (please correct this if wrong), and now I am trying to use the parallel package https://hackage.haskell.org/package/parallel-3.2.1.0. I am not getting any better performance in the sense that if I try to compute the 100th Fibonacci number, it is still computing , using 4 cores, several minutes later. Here is my attempt. Please show me how to use this library right. from src/FizzBuzz.hs fizzBuzzFib :: Integer -> [Text] fizzBuzzFib ub = parMap rdeepseq fizzbuzz $! fibSeq ub from src/FizzFub.hs fibSeq :: Integer -> [Integer] fibSeq ub = withStrategy (parBuffer buffer rdeepseq) $ genericTake ub fibbwhere buffer = 100 fibb :: [Integer] fibb = 0 : 1 : zipWith (+) fibb (tail fibb)