Here we describe the characteristics of QPC on different Windows versions to help you maintain software that runs on those Windows versions. QPC was introduced in Windows 2000 and Windows XP and has evolved to take advantage of improvements in the hardware platform and processors. Resolution, Precision, Accuracy, and Stability.Low-level hardware clock characteristics.QPC helps you avoid difficulties that can be encountered with other time measurement approaches, such as reading the processor’s time stamp counter (TSC) directly. Consider using GetSystemTimePreciseAsFileTime when you want to time-stamp events across multiple machines, provided that each machine is participating in a time synchronization scheme such as Network Time Protocol (NTP). QPC is typically the best method to use to time-stamp events and measure small time intervals that occur on the same system or virtual machine. Each of these operations involves a measurement of activities that occur during a time interval that is defined by a start and an end event that can be independent of any external time-of-day reference. These performance measurement operations include the computation of response time, throughput, and latency as well as profiling code execution. Time stamps and time-interval measurements are an integral part of computer and network performance measurements. To retrieve time stamps that can be synchronized to an external time reference, such as, Coordinated Universal Time (UTC) for use in high-resolution time-of-day measurements, use GetSystemTimePreciseAsFileTime. QPC is independent of and isn't synchronized to any external time reference. For managed code, the class uses QPC as its precise time basis. For device drivers, the kernel-mode API is KeQueryPerformanceCounter. The primary API for native code is QueryPerformanceCounter (QPC). Windows provides APIs that you can use to acquire high-resolution time stamps, or measure time intervals.