It's not really surprising that removing the blood and having fewer enemies on screen allows to increase the resolution:
http://www.neogaf.com/forum/showpost.php?p=17635322&postcount=4021
As for the framerate, there were some bad parts in the 360 version, but the PS3 version seems to have tearing instead...
My Mario Kart Wii friend code: 2707-1866-0957







