The Shield Portable has a Tegra 4 processor, which was top of the line when it came out. I suppose that's a bit old by now, but I can emulate through Nintendo 64 and Playstation 1 without any problem. Sega CD, NeoGeo, and MAME all work great, too.
Dreamcast and PSP as well. It has more power than it is given credit for. You can also get an overclock kernal but I just haven't felt the need to yet.
Cool people I have bought stuff from on this board: orrimarrko kyosuke75 dave2236 video_game_addict cloudstrife29661 NESCollector75