You can get almost full speed on the PSX emulator on new 3DS at least. FF7 runs at 50fps.
Since I imagine the N64 uses similar processing to the 3DS more so than PS1, and how PS1 handles more data at once, I'd expect a full speed N64 in the next two years.
Since I imagine the N64 uses similar processing to the 3DS more so than PS1, and how PS1 handles more data at once, I'd expect a full speed N64 in the next two years.