I have to say this in defense of Windows 8/8.1.
I run 5 monitors with two graphics cards. 16 GB DDR3 Ram. 2 SSDs. 6 core CPU.
I have a dual boot system, so all the hardware is the same on both Windows 7 and Windows 8.
Using WindowFX ;
On Windows 7, windows dragged to the monitors attached to the second gfx card go invisible until you release. On Windows 8, that doesn't happen.
On Windows 7, running Deskscapes on 5 monitors is draggy/jumpy. On Windows 8.1, smooth as silk.
All the same hardware and drivers updated.
Windows 8 simply handles resources better. No doubt about it.
I have been using 8 or 8.1 as my main OS for nearly a year now, or at least 6 months. Very few problems, now that Stardock has "fixed" 8 to look more like 7.