Thats true.
Also, measuring complexity with the number of characters, cars, effects isn't accurate.
A hundred 50-poly characters is easier and faster to make than one character built from a million polygons. This would apply to the car as well. As for effects, well, depending on the effect, the complexity to perform each would also vary.
And I haven't gone into animating yet...
C. P. U. Its not a big processor... Its a series of pipes!