Merge pull request #259 from NickCaplinger/patch-1

Add missing word

tutorials/3d/3d_performance_and_limitations.rst

@@ -13,7 +13,7 @@ usability and flexibility. Some practical examples of this are:
 -  Rendering objects efficiently in high amounts is easy, but when a
    large scene must be rendered it can become inefficient. To solve
    this, visibility computation must be added to the rendering, which
-   makes rendering less efficient, but at the same less objects are
+   makes rendering less efficient, but at the same time less objects are
    rendered, so efficiency overall improves.
 -  Configuring the properties of every material for every object that
    needs to be renderer is also slow. To solve this, objects are sorted