The CPUMeter class shows you CPU utilization:

CPUMeter mtr = new CPUMeter();
... // do some heavy lifting
double usage = mtr.GetCpuUtilization();
Console.WriteLine("Done. CPU Usage {0:#00.00} %", usage);

You can also do it for a specific process id:

CPUMeter mtr = new CPUMeter(123);
... // do some heavy lifting
double usage = mtr.GetCpuUtilization();
Console.WriteLine("Done. CPU Usage {0:#00.00} %", usage);

One of the problems with the default timer capabilities in .NET is that it doesn't go down to the exact nano-second level - which is critical for applications such as unit testing - but instead rounds out the milliseconds. Adapdev.Diagnostics provides a class for low-level timing, with the option of several different timer types:

Below are examples using the various approaches:

Minutes

IPerfTimer t = PerfTimerFactory.GetPerfTimer(PerfTimerType.MINUTES);
t.Start();
Thread.Sleep(1000);
t.Stop();
Console.WriteLine(timer.ToString() + ": " + t.Duration);

// Output is: 0.0166666666666667

Seconds

IPerfTimer t = PerfTimerFactory.GetPerfTimer(PerfTimerType.SECONDS);
t.Start();
Thread.Sleep(1000);
t.Stop();
Console.WriteLine(timer.ToString() + ": " + t.Duration);

// Output is: 1

Ticks

IPerfTimer t = PerfTimerFactory.GetPerfTimer(PerfTimerType.TICKS);
t.Start();
Thread.Sleep(1000);
t.Stop();
Console.WriteLine(timer.ToString() + ": " + t.Duration);

// Output is: 1000

Milliseconds

IPerfTimer t = PerfTimerFactory.GetPerfTimer(PerfTimerType.MILLISECONDS);
t.Start();
Thread.Sleep(1000);
t.Stop();
Console.WriteLine(timer.ToString() + ": " + t.Duration);

// Output is: 1000

Hi-Res Milliseconds

IPerfTimer t = PerfTimerFactory.GetPerfTimer(PerfTimerType.HIRESSECONDS);
t.Start();
Thread.Sleep(1000);
t.Stop();
Console.WriteLine(timer.ToString() + ": " + t.Duration);

// Output is: 0.522687052442292