Freezing Modifiers / Freezing Boolean

I thought Blender wasn't good at handling large numbers of polygons. But I came across a video where the author says that the brakes occur due to the fact that when you move an object, the modifiers are updated every time. Is it possible to add a function for freezing modifiers so that they are not constantly recalculated, or so that modifiers work relative to the mesh, and not the object? Here is a video that clearly shows that the brakes occur due to recalculations of modifiers - youtube.com/watch