Holy cow, I wrote a book!
The QueryPerformanceCounter function has
been the subject of much rumor and innuendo.
In response to all the confusion,
the kernel folks put together a page which
tries to settle the controversy once and for all.
discusses the history of QPC over the ages,
the problems it had on earlier versions of Windows
or older firmware
(which is probably where a lot of the myths started),
its interaction with hypervisors,
offers guidance on how to use it and its alternatives,
and includes a very nice Q&A.