ATI Radeon HD 4650 poor performance in battery mode

"ATI graphical cards on laptops are relying on the PowerPlay ""technology"".

It adjusts the frequencies from the GPU and its memory, to save power. You can deactivate this option in the Catalyst control center which should be installed with your drivers:

If you deactivate it simply, the card will be on maximum performance all the time. You can also enable it, and choose yourself which performance level should be used depending on the power status (if I remember good, there is also an intermediate step between max and min, on ATI power management, which could be eventually enough for some programs, and would allow to save power compared to the maximum, in battery mode)."