Placebo effect....
. Seriously though I'd need to test some games out on both to be sure: we're apparently talking full speed with RA SNES? Played the first half of Castlevania IV and it slows to a crawl at certain points, several times..... Mario World (minor) slowdown, Kirby SuperStar slowing to a crawl... Hell even Yoshi's Island slows... These games don't slow to the same extent on the actual hardware at these points, trust me I'm well versed with the games, but they do 'seem' to be slower on vWii than on regular Wii.