My very old Intel PC has had a few things done to it, as I don't fool around with cars any more I like fooling around with it to go 'faster', perform better as cheaply as possible. ????
First was to find a better CPU, I did, a Q9400, it improved stuff, then bought a 250GB SSD, installed my W10 on it and used the 500BG HDD as storage. What a difference that made to start up and shutdown times, increased the RAM from 4 to 8GB, max for the board, no real noticeable difference but am sure it has. The biggest difference in actual use was upgrading the CPU again, I found a 10+ year old 3.0 Ghz Xeon E5450, that made it whizz.
So, for sure, I would never have an HDD running things, my experiments have shown me first hand differences.
PS. Don't forget to check on LAN, I installed a 1GB expansion card in the PC, gone from 65Mbps to around 560Mbps, though I have just changed the motherboard which has a 1GB as standard, same result.. ????