Vertexbuffer.com

If you are not running on an ATI card, you are probably running on an nVidia card; If that is the case then NvPerfHud is a very valuable asset to you. The NvPerfhud will not only report information about the GPU’s percentage of idle time, it also will allow you to manipulate the graphics pipeline directly. If you have determined if you are GPU limited, then manipulating the graphics pipeline directly will help you determine the limiting bottleneck of your application by simply following a process and pressing some keys.

The NvPerfHud is available for free to anyone and you aren’t even required to be a registered developer. There is one catch that makes NvPerfHud somewhat inconvenient. In order to access the functionality of the NvPerfHud, you will need to download a specific driver that exposes these capabilities to the application. These drivers, although very stable, may cause some oddities in certain programs. If you can afford to have a dedicated machine for profiling, and it has an nVidia card, then installing these drivers is well worth the rewards you get from using NvPerfHud.