Meshes - Minimize polygon count

Every polygon in a mesh entails a rendering performance hit insofar as a GPU needs time to process and render each polygon. Consequently, it's sensible to minimize the number of a polygons in a mesh, even though modern graphics hardware is adept at working with many polygons. It's a good practice to minimize polygons wherever possible and to the degree that it doesn't detract from your central artistic vision and style:

There are many techniques available to reduce polygon counts. Most 3D applications (such as 3Ds Max, Maya, and Blender) offer automated tools that decimate polygons in a mesh while retaining their basic shape and outline. However, these methods frequently make a mess of topology, leaving you with faces and edge loops leading in all directions. Even so, this can still be useful for reducing polygons in static meshes (meshes that never animate), such as statues, houses, or chairs. However, it's typically bad for animated meshes where topology is especially important: