I've got a 1ghz 15" PB. I recently upgraded the memory to 1gb. Whenever I'm on battery power, I experience annoying response delays when working in Excel. For example, double tapping on the track pad and then dragging the scroll bar results in no apparent response for a second or so (seems like an eternity though), then the bar suddenly jumps. There are similar delays for many other actions, such as dragging a cell to fill adjacent cells, applying formatting such as bold or underline, etc. I see the little clock while I'm waiting. Some facts: -This was happening even before I upgraded the memory. -This happens even with no other applications open, and with relatively compact spreadsheets. -It happens whether the batter is fully or only partially charged. Also, I properly calibrated the battery when I first got the machine a month ago, and I get plenty of battery life from each charge. -I've tried the "highest performance" energy saving choice, and the custom choice with "highest" processor performance selected. I get the delays regardless. -With the power adapter connected, all of these delays go away, and response is instantaneous. Does anyone have an idea what could be causing this? It's a mystery to me that it only happens on battery power. Thanks for any help. This is driving me NUTS!