Why Is My Computer Running Slow

I’m posting this video as an effort to get some insight on what could be the root cause of a laptop video problem I am experiencing. I purchased this laptop as a replacement for the same model laptop from ebay for around $100.00 and I expected some issues, but based on the description the laptop at least seemed like it had no issues. I used it for about a day with everything looking fantastic. After about a day, i noticed the screen started jumping/shaking. Since I was doing some work to the laptop (installing my old hard drive) I used a screwdriver which was magnetized to retrieve the screws without losing them. When the screen first started flickering, it seemed like when what appeared to be one screw was screwed in, the screen would jump consistently. When the screw was removed, it would not. I drew the conclusion that the one screw caused the problem, and the flickering ceased for about 2 days or so. I continued using the laptop with only a couple of screws in the bottom of the laptop. The issue returned, and it seemed as if when the computer is turned on after being off long enough to cool off, it wouldn’t flicker, but when the computer warms up after about 10 minutes, the issue returns full blast. The only thing I can determine that relieves the issue is pressure on the area where the mousepad is in the middle of the computer. When pressing down (as shown in the video) the jumping ceases. When releasing, it goes back to jumping. Also, when the screen saver comes on …