Thanks alot, Bulat! New results are much better: ------------------------------- test_list = [L8.pack "Hello world!"] ++ [L8.replicate 1000000 ':'] ------------------------------- The results are (iterations_count, microseconds): (1000, [300 +/- 200 , 18400 +/- 100]) (10000, [1030 +/- 10 , 19950 +/- 50 ]) (100000, [9100 +/- 100 , 55000 +/- 15000]) (1000000, [89850 +/- 500 ,185000 +/- 500 ]) I also played a bit with bang patterns, to make input stricter, but this gave the same result. ------------------------------- For the first test string time grow almost linearly, what can't be said about the second string. I still wonder if (and how) GHC optimizes the process. Belka -- View this message in context: http://www.nabble.com/estimating-the-speed-of-operation-tp22075843p22078560.... Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.