You haven't supplied enough information for us to give a good answer. What exactly are you trying to do to the file? There are undoubtedly ways to make your code run faster, but if we don't know what your code does, we can't suggest ways to optimize it. If you're reading line by line, for instance, you can speed things up some by reading multiples of the disk sector size and then splitting.

Short of that, get a faster hard disk, like holli suggests. This will most likely give you the largest speed improvement.