So I finally played Race-O-Rama (till the credits, played most levels in each world) on a Wii and I was not impressed. The game suffers from a low framerate. I was trying to figure out what the reason might be. I am almost confident that it is caused by a smoke effect and draw distance.
The draw distance is quite high and since the levels take place on dirty tracks, there is a lot of smoke. Now, GC and Wii have amazing smoke effects but this does not look impressive. Yet it somehow causes framerate problems (can smoke be displayed as polygons btw?) It is especially obvious right before the start of some of the Mario-Kart-like levels (yes, they do exist and they are the worst attempts at Mario Kart I have ever seen): the framerate falls to maybe 10. Once the smoke clears, and there is less camera movement (at the start of the race it turns around) the framerate goes up.
I have no idea what Dolphin is doing (I have not tried Dolphin), but I am confident those are not 60fps. Maybe 12-20 on average.
HOWEVER the last world in this game is Toyko which takes place at night and the tracks are surrounded by large buildings (low draw distance) and there is no smoke! (normal city streets) And there it is: a steady framerate of probably 30. Whoever ported this game did not know about the Wii or didn´t care to make a few changes for a much better experience (different smoke, maybe fog instead of a high draw distance).
It´s too bad because the gameplay is actually decent/good. I really like the combination of turbo and sliding. The game also has two-player splitscreen modes and those have a noticeable drop in draw distance (trees popping up; i personally much prefer fog).