Acer Laptop/Fresh install mysteriously slow. a few questions too

So, an update. A little too early to mark as resolved but definitely almost there.
Yesterday I ran several free HDD testing utilities against the HDD in question (hooked up externally to the OMEN laptop I am using right now) and compared the results to the same tests ran against two other old HDDs hooked up the same way (and also tested the internal drive of the OMEN. While obviously the external drives had slower speeds to the internal one, the results were similar. Further, the other tests, including another chkdsk found nothing wrong. Nevertheless, I wiped the drive clean and did a deep format then popped it back in the parent laptop and installed Windows from the setup guide you referenced. As you might have expected, 3 hours later, no difference. So, I took one of the old drives I used to compare against and wiped it clean and threw it into the laptop and installed windows. I could tell just as it asked for input, that it was starkly faster than the other (Toshiba) HDD. In fact, after it asked me how to install windows, I began typing this reply and just now it finished. So clearly, you all were correct, the HDD was pooched, but can you explain to me how?
How does a hard drive (that is making no noises and passes all tests - although I didn't try one from Toshiba) fail in such a way that it even slows down the on-screen echo of what I am typing or cause programs that should already be in RAM to take about 25x as long (literally) to open?
Thanks again for all this guidance.

Buy a SSD. They are six times faster than a HDD.

Megahertz said:

Buy a SSD. They are six times faster than a HDD.

No doubt, but there's no need fore me to buy a Ferrari if I live on a gravel road and already have a 4x4.

majbach said:

No doubt, but there's no need fore me to buy a Ferrari if I live on a gravel road and already have a 4x4.

I understand your reluctance to spend any $ on an old PC. If you're satisfied with the performance, be happy. I would never encourage anyone to spend $ to improve something they're happy with.

Just as an FYI, I recently purchased a 240GB Kingston SSD for $40 Canadian, delivered from Amazon. My 10 year-old Dell now boots in 15-20 seconds, or wakes from Hibernation in about 6 seconds. I'm happy with the improvement.

W10 Tweaker said:

I understand your reluctance to spend any $ on an old PC. If you're satisfied with the performance, be happy. I would never encourage anyone to spend $ to improve something they're happy with.

Just as an FYI, I recently purchased a 240GB Kingston SSD for $40 Canadian, delivered from Amazon. My 10 year-old Dell now boots in 15-20 seconds, or wakes from Hibernation in about 6 seconds. I'm happy with the improvement.

Good advice. I have three laptops and another for work. I invested $$$ in this OMEN and really like it so it is my primary computer. The one that had the pooched HDD seemed slow right from the store; I thought it was bloatware but it's still less than stellar. In the last decade, despite heavy use, I've never had a failure or had to install Win 10 or Win 7 so this was as much a learning experience.
The drive I used for a replacement I found in a parts drawer and I have no idea where I obtained it. It's larger and older than the one that failed but it seems to work fine. When it goes, I'll go grab an SSD. I can always in the future in another device.
Thanks again for the input.