Laptop batteries aren't the exactly the tortoises of the gadget world: they start out strong, then get weaker and weaker until eventually you can't even make it through an episode of 30 Rock on a full charge. So some users have taken up the practice of popping out their batteries while on AC power to try to eke out a few more months of juice. But the guys over at Gearlog tested performance on their new MacBook Pro with and without the battery, and here's the lesson: leave that battery in the computer where it belongs.
While benchmarking some memory, Gearlog found that processor performance is a whopping 37% lower on a MacBook Pro running on AC alone. Cinebench R10's multiprocessor test got a battery-less Pro a score of only 3,504, while with the battery it scored 5,549. They contacted Apple to find out what's going on, and Apple admitted that the performance difference is intentional, explaining that it "prevents the computer from shutting down if it demands more power than the A/C adapter alone can provide." Sounds a little fishy to me, but it doesn't really matter: Apple took a lot of care with that battery, and if you know what's good for you, you'll leave it be. [Gearlog]