WebGLRenderLists: No need to call sort if array has 1 or less elements.

src/renderers/webgl/WebGLRenderLists.js

@@ -103,8 +103,8 @@ function WebGLRenderList() {
 
 	function sort() {
 
-		opaque.sort( painterSortStable );
-		transparent.sort( reversePainterSortStable );
+		if ( opaque.length > 1 ) opaque.sort( painterSortStable );
+		if ( transparent.length > 1 ) transparent.sort( reversePainterSortStable );
 
 	}