What's a very easy C++ profiler (VC++)?

I suggest a very simple method (which I learned from reading Mike Dunlavey's posts on SO):

Just pause the program.

Do it several times to get a reasonable sample. If a particular function is taking half of your program's execution time, the odds are that you will catch it in the act very quickly.

If you improve that function's performance by 50%, then you've just improved overall execution time by 25%. And if you discover that it's not even needed at all (I have found several such cases in the short time I've been using this method), you've just cut the execution time in half.

I must confess that at first I was quite skeptical of the efficacy of this approach, but after trying it for a couple of weeks, I'm hooked.

VS built in:

If you have team edition you can use the Visual Studio profiler.

Other options:

Otherwise check this thread.

Creating your own easily:

I personally use an internally built one based on the Win32 API QueryPerformanceCounter. You can make something nice and easy to use within a hundred lines of code or less.

The process is simple: create a macro at the top of each function that you want to profile called PROFILE_FUNC() and that will add to internally managed stats. Then have another macro called PROFILE_DUMP() which will dump the outputs to a text document.

PROFILE_FUNC() creates an object that will use RAII to log the amount of time until the object is destroyed. Both the constructor of this RAII object and the destructor will call QueryPerformanceCounter. You could also leave these lines in your code and control the behavior via a #define PROFILING_ON