In JSF 1.1 there are the following related methods in UIComponent:

int getChildCount()
java.util.List getChildren()
javax.faces.component.UIComponent getFacet(java.lang.String name)
java.util.Map getFacets()
java.util.Iterator getFacetsAndChildren()

JSF 1.2 adds the following:

int getFacetCount()

In UIComponent, there is the List of children, and the Map of facets. Both of these are only allocated as needed. The problem is that their getter accessors guarantee to return a non-null List and Map, respectively. So, even if a component has no children, nor any facets, just calling getChildren() or getFacets() will now take up memory. In JSF 1.2, they audited their code, and replaced any access to their children with a call to if( getChildCount() > 0) { getChildren() ... }. Similarly, even though we may not be able to use getFacetCount(), we should prefer calling getFacet(key) instead of getFacets().get(key).

In order for this to make a difference, we have to fix EVERY SINGLE access of the children and facets. With modern IDEs this should be straight-forward.