I am currently running the latest CM7 Nightly and am also an avid Angry Birds player. I have tried several kernels and so far I have found the best one is the Tiamat_EVO-v4.0.6-sbc. It gives me phenomenal battery life.
I charged my phone to 100%, then left it off the charger for 8 hours while I slept and it was only at 94% with wireless on, mail notifications running, and an alarm set. I played Angry Birds (all three versions) and some other games, checked my email, and did some browsing for about 4 hours and it only dropped to 74%. Throughout the day with some lighter usage, at about 15 hours, it was only at 65%.
Of course this is just MY experience. As with all phones, roms, and kernels, experience WILL vary. So just keep experimenting until you find what works for you.
I should also mention that my cpu settings are SMARTASS 128/1075 mhz which may contribute greatly to the battery life.