Overall lack of performance, looking to clean system

Long time leecher here, looking to actually get into the community.. starting with asking for some advice.

I'm wanting to get back into gaming, but I've been really lazy on computer security lately and I'm looking to get my laptop back to the best performance I can get out of it.. but I'm at a loss as to where I should start. Any help is appreciated.

Also, on a small sidenote, I've noticed when in-game I get CPU spikes from audiodg.exe. They're not huge spikes, the process goes from 1-2 to around 10. These spikes seem to create horrible drops in FPS when they happen, though.
 
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