Since we don't know what you do to a file, how can we asses the "30 minutes to process 30Mb"? Perhaps you have been very clever to do the task at hand in just 30 minutes. Perhaps you have used an extremely slow algorithm, and it could be done in a few seconds. Who knows? Well, you know, but we don't.

But I remain, as long as you think that 30 Mb is a "very large file", you're not from this era.