Fast Reading from File

I have a need to read large lists of numbers from a file and operate on them. I tried the following: read' =do s <- readFile "temp" print $ sum $ map (fst.head.readDec)(lines s) But this is quite slow even for 1000 numbers. Are there any other ways to do it faster? Will it help if a C function does the reading and Haskell calls that. I have to use Hugs. Thanks, Saswat