On Windows NT your primary tool will invariably be the Windows NT Performance Monitor or a similar product. Performance Monitor is designed to pinpoint the majority of performance problems. You can think of Performance Monitor as a broad, horizontal tool that lets you look at a wide range of system components. But some problems require other tools, which you can think of as specialized, vertical tools for intensive monitoring of specific aspects of your system or application. Performance Monitor can lead you to the correct tool for the next phase in your investigation. This method of using Performance Monitor first, and then a more specialized tool, will always save you time.
Another tool that is quite handy for quickly assessing the status of programs on your system is PView, available on the floppy disk provided with this book. PView shows what programs are currently running and gives some basic information about each. With the exception of a few items included in PView to aid in debugging applications, all the data items in PView are also available in Performance Monitor. But PView is a bit simpler to start and displays data in a different way that's quite handy for a quick glance at system status.
As mentioned above, additional tools exist for tuning individual applications. Some of these can also be an aid to tracking down performance problems. So be sure to familiarize yourself with these tools even if you do not plan to write any applications yourself.