My new PC has windows 7 on its SSD, and starts up faster than my laptop running windoze 8. But that's more like fixing a software problem with a hardware problem soo... lol.
The major problem I have with windows 8 is that they attempted to make a cross platform interface for tablet integration. Which is fantastic for tablet users, terrible for desktop users. Windows 8 just loves to try to remind me that the desktop is just some application; splatting tons of annoying other ones at me in the processes. I literally have no use for anything that isn't running on the desktop, and I can't get rid of these stupid extra applications.
Windows 8.1 attempts to make windows 8 more PC and less tablet, but still maintains those problems. Also the last time I checked it was buggy as all hell; lots of extremely PC breaking glitches that my pal Nexus had the misfortune of experiencing while we were trying to play Civ5. Apparently in certain fullscreen games the processor goes up linearly to 100% CPU usage, until you alt tab, and it jumps back down to what it should be. Apparently after some google searching, this is a common issue. He downgraded back to 8.0 and the bug was gone. There were other extremely annoying things I remember him complaining about, but I didn't actually get to see them.
Windows 7 is refined and works exactly the way you would want and expect it to. If you have a problem with speed then buy faster hardware, adopt the age old practice of fixing software with hardware; it's worked so far and it'll work forever.
