Ok, so Mednafen is suggested to have a 4 core. One could also make the argument that it is also a very new emulator since that part of Mednafen is less than a year old and could still use some optimization. That is tough to say though since the Saturn is such a complicated beast with it's dual cpu and dual vdp that it will need the raw power.
Higan / BSnes is still single core and so is PSX. To scale PSX beyond 2x with good speed use a hardware renderer and that then depends on the video card.
Bottom line though is the OP is working on a budget based off their post. So as long as they keep their expectations in check the G4650 would handle most things just fine, just avoid the newer cutting edge emulators.
Of course a more expensive and modern i5 / i7 with high clock speeds would be better but you pay a lot more for that. It's always a budget vs expectations question.