Update: So I installed Bitcoin Core on the other PC I mentioned (Core i7 4790K etc) Yesterday and it's almost finished syncync now, downloaded over 75GB since Yesterday and most of the time the PC actually was sleeping as Windows 10 in their eternal wisdom did not believe Bitcoin Core was doing anything and let the PC enter hibernation.

In other words, on the more powerful PC, connected to the same network as the core i7 laptop, it's exponentially faster. Probably around 15x+ faster...