The difference in the Interface of Win8 Vs Win7 not that it will 'improve the performance' of your applications, it won't. What it can do, which many of us dislike, is become more of a headache for Keyboard / Mouse use since the UI is based on using a 'touchscreen'. Some people really can adjust to this (I dunno how) and can't see living without Win8 interface, I personally gave it several tries and find it is too cumbersome for K/M.
If you want improvement for your software, you need to center around the GPU and Memory, on the given your not on a 'generic' HDD of 5400RPM. Both will improve time and speed of editing, but still rely on the 'slowness' of the HDD to read off of. Which is why most people look to SSD + HDD mulitple drives, putting the software on the SSD to boost the 'feel' and speed but HDD to do the storage.