In the first lesson, you created a simple 2D dynamic fluid. 3D fluids intrinsically require extra data to define them, which can make them very complex. This extra data can slow a dynamic simulation exponentially because more calculations (solving) must be performed at every step of the simulation. For a less memory intensive effect, you could use a 2D fluid (with less data), or you could create a 3D non-dynamic effect.
In non-dynamic fluid effects, the fluid property values are predefined within Maya and stay constant over time, which means they don’t have to be recalculated. You create the appearance of the fluid by texturing a special fluid shader that is assigned to the fluid. This shader is built into the fluid for better performance. If you want the fluid effect to have motion, you can animate (keyframe) the texture attributes. Because Maya doesn’t solve the fluid dynamics equations, rendering this type of fluid is much quicker than rendering a dynamic fluid.