Hello! I've had a similar problem with text processing discussed on the list some time ago (a topic about implementing a spellchecker). To keep things short'n'simple: built-in Haskell Strings are inefficient as they're simply lists of Chars, i.e. a String is in fact just a [Char]. The usually suggested solution to this problem is using the ByteString type which comes from bytestring package. It's probably all nice when you only need ASCII/Latin encodings, but it bite me when processing Unicode (e.g. Data.ByteString.UTF8 doesn't have a words function, though Data.ByteString has one). However, the performance is good. The best solution as far as I have researched is the text package and type Text. It ought to support Unicode as far as I remember and has got all the useful list-like functions. As I hadn't yet had an occasion to play with it before, I took your code and adapted it to use Text and Text.IO. Let me know what are the results, as I haven't got any test set to compare the speed before and after the modifications. === CODE -- Problem id: HASHADQI import qualified Data.List as List import qualified Data.IntMap as Map import Data.Maybe import Data.Text (Text) import qualified Data.Text as T import qualified Data.Text.IO as T type Person = (Text,Text,Text,Text) type IntPersonMap = Map.IntMap Person main = do input <- T.getContents seqAction Map.empty $ T.lines input seqAction :: IntPersonMap -> [Text] -> IO IntPersonMap seqAction m [] = return m seqAction m (l:ls) = do m' <- doAction m l seqAction m' ls doAction :: IntPersonMap -> Text -> IO IntPersonMap doAction m cmd = do case T.unpack (T.take 1 cmd) of "a" -> doInsert m $ T.words cmd "d" -> doDelete m $ T.words cmd "i" -> doInfo m $ T.words cmd "q" -> doQuery m $ T.words cmd [] -> return m doInsert :: IntPersonMap -> [Text] -> IO IntPersonMap doInsert m [_, idText, fn, ln, bd, pn] = do let id = read (T.unpack idText) :: Int if Map.member id m then do putStrLn $ "ID " ++ show id ++ " ja cadastrado." return m else return (Map.insert id (fn, ln, bd, pn) m) doDelete :: IntPersonMap -> [Text] -> IO IntPersonMap doDelete m [_, idText] = do let id = read (T.unpack idText) :: Int if Map.member id m then return (Map.delete id m) else do putStrLn $ "ID " ++ show id ++ " nao existente." return m doInfo :: IntPersonMap -> [Text] -> IO IntPersonMap doInfo m [_, idText] = do let id = read (T.unpack idText) :: Int case Map.lookup id m of Just (fn, ln, bd, pn) -> do putStrLn . show $ T.unwords [fn, ln, bd, pn] return m Nothing -> do putStrLn $ "ID " ++ show id ++ " nao existente." return m doQuery :: IntPersonMap -> [Text] -> IO IntPersonMap doQuery m (_:qs) = do let test = (\x -> foldl (&&) True $ map ($x) $ makePredicate qs) result = Map.filter test m putStrLn $ unwords . map show $ Map.keys result return m makePredicate :: [Text] -> [(Person -> Bool)] makePredicate [] = [] makePredicate (q:qs) = case (\(a,b) -> (T.unpack a, b)) (T.break (==':') q) of ("fn", x) -> (\(fn,_,_,_) -> fn == (T.drop 1 x)) : (makePredicate qs) ("ln", x) -> (\(_,ln,_,_) -> ln == (T.drop 1 x)) : (makePredicate qs) ("bd", x) -> (\(_,_,bd,_) -> bd == (T.drop 1 x)) : (makePredicate qs) ("pn", x) -> (\(_,_,_,pn) -> pn == (T.drop 1 x)) : (makePredicate qs) === END CODE Regards, Radek Szymczyszyn