Maybe it came down the silk road by camel? Sounds like it sat in someone's warehouse for a while.
I have no issues on my Macbook with 8GB, though because it was on special offer, this iMac has – and I suspect unnecessary – 24GB. I was going for 16GB, but that time it was about £20 more for the additional.
Macs of different flavours can work together, I have High Sierra, Catalina, and Big Sur at the moment.
If I computer is running that slowly, I'd check on exactly what is running.