How to process 360 GB file within a minute

I have processed a 3 GB binary file within three minute using a single thread.Here processing meant that I have read the file and loaded onto memory and applied a small buisness logic while processing the data.The program is taking 3 minutes as a processing time If I use multithreading in the program, it is taking 4 minutes (more time) to process that data . If we compre the two procesing time(single thread ,multithreads) the multithread program is taking more time.Generally speaking multithreading should give good performance .Here performance is meant that processing time. Here I observed the multithread programing while switching between the threads ,the threads are taking some tiny time.In the tiny time those theards are in idle state. The above program is only for testing 3 GB data. But my intension is to process the 360 GB data with a minutes. Please give your thoughts about it.

A CPU can only do one thing at a time, I really don’t think multi threading is going to help you and I would expect to see an increase in processing time using this approach for this type of work, using multiple threads is only a benefit when a processes is not making the best use of a CPU for example multiple threads may help when using sockets as you CPU spends a lot of time waiting for responses, time where other threads could be using the CPU. On the other hand processing data will not leave your CPU idle for very long if at all making switching between threads costly and of no benifit. I think you have two options one is to add more CPU’s to your machine or concentrate on making the single thread as efficient as possible, not sure that you are doing with it, but 3 minutes for 3 GB doesn’t at all bad to me.