How does it "struggle"? My 2012 i7 has no problems with Safari. It also runs Final Cut Pro and Logic Pro quite well. I run Sierra from an external iTB Samsung T3 SSD. I have 16gb, but I don't understand why Safari would need more than 8gb. Are you doing something especially intense in Safari?
I do tend to keep a lot of tabs and windows open owing to work i do - I find that over time (say an hour) the CPU usage suddenly zooms up to 200%+ and I have to force quit Safari or if I'm too late wait for it to calm down as machine freezes, or reboot. Safari Technology Preview is also prone to this.
The memory failure is a known fault with the 2012 Mini - the bottom socket has failed probably due to a connection with the motherboard (nothing wrong with the ram itself). However, I was getting the same Safari problem with 16GB ram.