The previous post is here.
What a strange turn of events! Also, I'd like to thank everyone that replied in the previous thread. You all are so very well informed and helpful!
I was preparing to make the transition from my current iMac to the one suggested here. I have 2 external hard drives. One of them is a 6 TB drive that is used for backups. The other is a 500 GB drive that I use for media storage. I bought this media storage drive around 5 years ago so the official site, probably, isn't up to current specs.
To explain more, I moved all of the media files from that 500 GB external drive back to my iMac since it supports 1 TB of storage. No problem there and I still have plenty of additional storage.
Slowly I began to notice that my iMac was responding a little faster for some things. Intuitively, I decided to 'eject' the 500 GB external hard drive and physically unplug it from my iMac.
After I did this, my iMac began responding to anything with lightning speeds! I guess this problem is solved and I have no idea what may have caused this in the first place.