Dear reader, I decided to do a little project which is a simple search and replace program for large text files. Written in Haskell, it does a few different regex matches on each line and stores them in a leveldb key-value store to create a consistent/reviewable search-replace index. It should provide for some simple/brute-force anonymization of data and therefore I called it hanon (sorry, could not think of a better name). https://github.com/BigDataRepublic/hanon The code works, but I've done some benchmarking to compare it with Python and the code is about 80x slower then doing the same thing in Python, making it useless for larger data files. I'm obviously doing something wrong. Could you give me tips on improving the performance of this code? Probably mainly looking at https://github.com/BigDataRepublic/hanon/blob/master/src/Mapper.hs where the regex code lives? Greetings, Bram