This subject is true for all 3D apps with render engines or stand-alone render engines like Maxwell.

The 3d term for having different texture maps based on distance from the render camera is called mip-mapping - it's really heavily used by 3d game render engines as well.

As GK notes above, Carrara does use a spooler scheme to manage textures but different resolutions is faster at render time in my experience.

On still, screen resolution imagery there is not going to be a big difference in time or quality unless you bring the camera right up to the object with the texture map. However, for print/lithographic quality still images, there will be a significant change in render time based upon map resolution.

Even greater still will be the difference during an animation render. In fact, in can make a difference of days during the final output.

Carrara doesn't have a mip-mapping capability built into it but you can manually manage texture maps to accomplish it. There is a free shader plug-in that accomplishes mip-mapping and it can be found here.