Q. Are uniform Fields less compute intensive than unstructured Fields?

A. It depends on what you're doing.

If you're rendering the data, unstructured Fields are less compute intensive than uniform Fields because all of its coordinates are there; they do not have to be computed.

If you're visualizing the data (slicing or isosurfacing it, for example), uniform Fields are faster because you don't have to do things like compute nearest neighbor (because it's the next element in the array).