Phaser 2.4.7 has some new toys, including this, which should simplify optimizations:
outOfCameraBoundsKill is a new boolean property that all Game Objects with the InWorld component has. If autoCull and this property are both true then the Object will be automatically killed if it leaves the camera bounds (thanks @jakewilson #2402)
Phaser 2.4.7 has some new toys, including this, which should simplify optimizations: