You need to identify the bottleneck. For example, is the I/O (disk) system running at 100% speed? If so, you won't be able to raise your CPU usage because you'll be waiting for I/O. (Unless you have some CPU-intensive task you can perform while waiting for I/O.) On the other hand, if I/O is not running at maximum capacity, and CPU is at 5%, then there must be something else slowing down your program.