Performance improvements isn't like a really huge difference.
Let's See How Windows 8 Performs Against Windows 7
You could probably feel the improvements if it isn't butter smooth in windows 7. (Yea my processor is that old)
@WhatThePho there seems to be some issues with some BIOSes maybe try to find if there is any update for your BIOS?
Some things you can do
powercfg -lastwake (Check what device last woke your device)
See if the device has a wake option in the device settings
Check you power option advance options and try disabling USB selective suspend and also disable wake timers under sleep.
More advance control of sleep/wake