• The speed varies between launches, so at first, I thought I was using an uninitialized variable somewhere; However, I checked my code, and all of my variables are initialized.
• I removed my timer class and measured FPS with Fraps. The application behaves the same way.
• My test application does the same thing on my friend's computer.
• I ran Very Sleepy, a profiler, and profiled the application in both speeds. There are differences between the two, but as I've never used a profiler, I don't really know how to interpret the information.
• Interestingly, Frank Luna's sample programs suffer from this same problem. Either we've both made the same mistake, or something is going wrong when I compile.

Do you even have a timer precise enough to measure 0.02ms?
Perhaps you should put this one aside and worry instead when you go from 15 to 17ms

.02ms is not a difference in speed that you should care about. That kind of a speed difference can be from so many thing because it is such a small amount.

If you are talking about “Introduction to 3D Game Programming with DirectX 9.0”, he uses timeGetTime() to get time readouts.
Always use QueryPerformanceCounter() for time functions.
Specifically, you should never use milliseconds to measure game time, and timeGetTime() can lag/stutter anyway.
Also, he is wrong to cast timeGetTime() to a float. Never cast your game time to a floating-point type. You may only cast deltas (time since the last frame).

That aside, there is nothing inherently wrong with your foundation yet.

Make a CTime class that uses QueryPerformanceCounter() to get time data and always measure game time in microseconds, and never ever cast the game time to a floating-point type.


L. Spiro

If you're going to recommend using QueryPerformanceCounter please please PLEASE also highlight the fact that it has known issues on modern PCs and that there is additional work you need to do to get around them. Otherwise it's a bad recommendation which should be ignored.

QueryPerformanceCounter will still go berserk on an Intel i7 running Windows 7 unless you know exactly what you're doing with it.

If you're going to recommend using QueryPerformanceCounter please please PLEASE also highlight the fact that it has known issues on modern PCs and that there is additional work you need to do to get around them. Otherwise it's a bad recommendation which should be ignored.

QueryPerformanceCounter will still go berserk on an Intel i7 running Windows 7 unless you know exactly what you're doing with it.