I have a file encryption program. When the program is encrypting files, it doesn't exceed 25% CPU usage, hence it is slow.
How can I make the OS assign to it more CPU load? (Such as WinRAR, when it compresses files, it reaches 100% from CPU load).
[Edit]: As my cores are 4, it doesn't use more than one core. How can I make it use the rest of cores?
Unless you are otherwise throttling the application it will use as much CPU as the OS allows it to - which should be up to 100% by default. I would guess that some other resource is the bottleneck.
Are you streaming the data to encrypt from a remote location? From a disk that is for some reason quite slow?