Laptop is ridiculously slow

I have an ASUS laptop with an Intel i7 4750hq 2ghz. It's a bit old, but it is somehow slower than its 5 year old age should be. I restarted it the other day and it took 46 minutes from the time I pressed restart to the time I could log in and when I try to open the start menu it takes a good 5-10 seconds to open. If you want to have 3 tabs of Chrome plus a game open at the same time, you have to be prepared to freeze for 5-30 seconds when you alt-tab or something. I have an Toshiba that's a couple hundred dollars cheaper and about 4 years older that isn't slow to this degree. If you asked me which of the two, disregarding the OS, was newer, I would say the Toshiba from 2012.

I checked all the drivers and they seem to be updated, I restart the computer regularly, have windows updated, have defragged, cleaned up files, and scanned for viruses/malware. I also got this from the "used" section of Best Buy, so my working theory is that somebody bought it, took the guts out and replaced them with cheap crap and returned it.

Does anyone have any ideas as to why this could be happening?