Emulation requires multiple times the power of said platform if you want it to run decently. A modern mid-range PC could handle PCSX2 for the most part aside from the real cpu intensive games like Shadow of the Colossus.
pcsx2 with the settings on default
Keep in mind with PCSX2 you'll have to fiddle around with the settings to get a number of games working properly.
And yet emulating the Wii doesn't require a beefy PC and the Wii U emulator is already playable.
Dolphin is an amazingly well made emulator that runs pretty damn well on even moderately decent PC's especially after the 5.0 update. CemU has made some impressive progress in a short span of time although it still has a ways to go.