The resolution of modern displays is such that you want specialized hardware doing the work. Modern font rendering engines run on GPUs as well now, because the

The resolution of modern displays is such that you want specialized hardware doing the work. Modern font rendering engines run on GPUs as well now, because the resolution increases faster than single threaded speed. GPUs are also more power efficient at many of these things, because while they use more power while running they get done sufficiently quickly that they end up ahead. That’s before you include the power savings from rapidly dropping the power mode. Note that this isn’t specific to AS, or even arm in general: every laptop wants to get to low power as fast as possible, because constant low-ish power is much worse than brief spikes that you can disable power between.