Documentation: Suggested edit adds clarity regarding when 'shouldComponentUpdate' is triggered and what the 're-rendering' process entails.

docs/11-advanced-performance.md

@@ -11,7 +11,7 @@ One of the first questions people ask when considering React for a project is wh
 
 React makes use of a *virtual DOM*, which is a descriptor of a DOM subtree rendered in the browser. This parallel representation allows React to avoid creating DOM nodes and accessing existing ones, which is slower than operations on JavaScript objects. When a component's props or state change, React decides whether an actual DOM update is necessary by constructing a new virtual DOM and comparing it to the old one. Only in the case they are not equal, will React [reconcile](http://facebook.github.io/react/docs/reconciliation.html) the DOM, applying as few mutations as possible.
 
-On top of this, React provides a component lifecycle function, `shouldComponentUpdate`, which is triggered before the re-rendering process starts, giving the developer the ability to short circuit this process. The default implementation of this function returns `true`, leaving React to perform the update:
+On top of this, React provides a component lifecycle function, `shouldComponentUpdate`, which is triggered before the re-rendering process starts (virtual DOM comparision and possible eventual DOM reconciliation), giving the developer the ability to short circuit this process. The default implementation of this function returns `true`, leaving React to perform the update:
 
 ```javascript
 shouldComponentUpdate: function(nextProps, nextState) {