> Quote - ... > > Edited to add: > > Sometimes people say normal maps save a lot of time, but when they say this, they do not mean save a lot of time compared to bump maps. They mean save a lot of time versus using real geometry. Bump *also* saves a lot of time versus using real geometry. Keep the comparison clear in your mind when reading posted opinions. Displacement is much faster than geometry. Bump is slightly faster than displacement. Normal is just a tiny bit faster than bump.

I think the saving of time refers more to the handling of the normal map, rather than render-time. When using bump or displacement maps and you want to use large or even unknown displacements, you cannot use 8 Bit pngs or jpgs anymore, otherwise you would get distortion due to colorbanding (see image, left normal; right bump). And the  whole process of rearranging, cutting and pasting texture maps is usually more inconvenient with 16 bit or hdr images, than with 8 bit images, simply because it is not so broadly supported by tools. With normal maps you just can use 8 bit pngs in most cases, which is a bonus in my opinion.

Another aspect in favour of normal maps is that when making materials, you can actually think in terms of the surface normal. Sometimes you just want to say: "For this piece of brushed metal, the polisher brushed counterclockwise, and so all normals should point slightly left". With bump maps you always have to come up with a geometry  (i.e. height-map) that would generate the normals you want to have.