<p>I am developing a C# program, and i have one function that consumes too much CPU. I would like to know a way to control this by code (not with any external application) and restrict the percentage of CPU usage. 
For example, if it uses 90% of the CPU usage, to make my app consume only a 20%, even if it becomes slower. It must be done automatically and from within the app.
If you provide a class, it would be fantastic.</p>

I don't know if you can do that, but you can change the thread priority of the executing thread via the
Priority
property.  You would set that by:
```
```
Thread.CurrentThread.Priority = ThreadPriority.Lowest;
```
```
Also, I don't think you really want to cap it.  If the machine is otherwise idle, you'd like it to get busy on with the task, right?  ThreadPriority helps communicate this to the scheduler.