Subject: System Time Precision, API Back-porting, and Kernel32.dll Updates Target Environment: Windows 7 (Pre- and Post-Windows 8 Release)
While the precise API is slower than GetSystemTimeAsFileTime due to the overhead of querying the hardware counter, it is significantly faster than the manual implementation of the same logic in user mode. On Windows 7, the performance hit is generally negligible for standard applications but measurable in tight loops. getsystemtimepreciseasfiletime windows 7 patched
GetSystemTimePreciseAsFileTime retrieves the current system date and time in UTC format with the highest possible resolution (<1µs). It stores the result in a FILETIME structure, which represents a 64-bit value counting the number of 100-nanosecond intervals since January 1, 1601 (UTC). Subject: System Time Precision