Right now we just use something like this
stopWatch.Start(); try { method(); } finally
Hmm, from Jon Skeet's answer to this question:
Timing a line of code accurately in a threaded application, C#
And also this article:
http://lyon-smith.org/blogs/code-o-rama/archive/2007/07/17/timing-code-on-windows-with-the-rdtsc-instruction.aspx
It seems like there's no simple way to do this.