I don't think this will help that much. There is buffering going on under the surface with stdio anyway and it should pick a good blocksize based on the device it is reading from.

The optimimum blocksize is returned by stat as Zaxo pointed out in a recent post. You could use an approach similar to this one (although the seeks are a really bad idea) and choose a multiple of that blocksize if your lines are usually bigger than it is but you would incur the overhead of breaking it up into lines. You are probably better off leaving that to the lower level routines.

-sauoq
"My two cents aren't worth a dime.";