Lenovo IP500 Horrible Performance. What's wrong?

I own a Lenovo IdeaPad 500 with an i7 Processor, 16GB of RAM and Windows 10 Home edition.

When I first bought it, it was filled to the brim with adware which I had to purge using Spyhunter and for a while it was running smoothly.

For the past few months, the laptop has been running very sluggishly, the start menu rarely ever works unless I enter a command into Powershell, applications often not responding, often getting the 'Blue Screen of Death', applications not responding and often having to kill pages in Google Chrome, even when running one application at a time. I've tried numerous registry and virus scans. Any idea what could be wrong here and how to fix it?

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