Cinebench R15 typically has an error margin of around 5%, though the impact of this can be reduced by taking an average of three runs, which is exactly what we have done. Looking at the single thread results we see a very slight increase in score from Windows 7 to 8.1 and then from 8.1 to 10. Certainly nothing to write home about, but this did have a greater impact on the multi-threaded results where Windows 10 was 7% faster than Win 7, though it was just 2% faster than Win 8.1.
Next up we have PCMark 7 with some interesting results: Windows 8.1 was consistently faster than Win 7 by a little over 100pts while Windows 10 was around 600pts faster on average. Further examination reveals that for whatever reason PCMark 7 was showing much higher "video playback and transcoding / video transcoding" performance under Windows 10 than the previous Microsoft operating systems. The result was almost twice as fast in hitting 9600kB/s.
The last synthetic benchmark we are going to look at is 3D Particle Movement and here we see similar results across all three operating systems. Windows 10 was on average the slowest, while Windows 8.1 provided the best results.