Are you one of those thrifty-types who's always looking for an angle, always trying to stretch every last penny? You know who we're talking about: Montel Williams bases whole episodes around you, the kind of person who reuses tea bags and separates sheets of triple-ply paper towels. Unfortunately, it now looks like you now have one less trick at your disposal. According to Zach Honig over at Gearlog, running your MacBook or MacBookPro without its battery (trying to squeeze out an extra month or two of battery life) will cause a significant performance decrease: we're talking upwards of 40 percent. When he checked Apple's knowledgebase, it turns out that this is by design -- processor speed is reduced when the machine detects that its relying solely on A/C to prevent it from demanding more power than the adapter alone can provide (and any nasty shutdowns that would result). We don't know if we buy this line of reasoning, but one thing is certain: if you know what's good for you, you'll leave that battery where it belongs.