Use the following trick to get 6,600 CP in about two minutes. There are two Behemoth-like enemies fighting each other at Gran Pulse. When you encounter them a preemptive attack will always happen. Use the following Optima set-up: Attacker/Enhancer/Enhancer. Wait until you get Haste and Fire elemental offense. Then, switch to Attacker/Blaster/Blaster. Kill the purple creature to make the white one is easier to defeat. Return near the save point to have them respawn.