It's like a hangover ( + sound issues)

So one improvement I've noticed with Win 10 (and I have no idea why this would be) is that games which my system could previously barely handle, now run much better/smoother/stable. It's almost like Win 10 upgraded (slightly) my hardware, or the hardware's abilities. The downside, however, is that upon exiting the game over the next 10-15 minutes the system operates as though it has 2 or 3 copies of the game still running in the background. A simple refresh can take as long as 3 minutes to happen, opening a folder can take about 5 minutes, and attempting to open my browser can cause the system to hang for a solid 15 minutes. Furthermore, while there is significant improvement in performance after this initial period, it literally takes about 3 days (with no games run) to properly recover so that everything happens in a flash (the speed I'm used to). During those 3 days it's almost as if everything I try to do must be checked and verified first (somewhat like after downloading a file and I have to wait for my antivirus to scan it first before I can open it). It's a slight delay, but it's noticeable nonetheless.

Less important, but also frustrating, is the sound issue I'm having. Pre win 10 upgrade I didn't have a need to touch my volume button in months. Now, it seems erratic and I'm constantly adjusting the volume. One video is barely audible with my volume turned to max, while another can be deafening with the volume almost at 0. Sometimes the volume barely changes at all even when I go from "1" to "100," while other times "40" might be too low, but "41" too loud. I've checked the drivers and they're up to date so I'm at a loss on what to do about this.

Thanks.