A method and apparatus for generating a series of frames with aid of a synthesizer to offload graphics processing unit (GPU) rendering within an electronic device are provided. The method may include: utilizing a GPU to perform full-rendering to generate a first frame in a color buffer, for being output to a display panel and displayed on the display panel; utilizing the GPU to generate a set of metadata of at least one subsequent frame in a metadata buffer; and utilizing the synthesizer to synthesize said at least one subsequent frame according to previous frame information and the set of metadata of said at least one subsequent frame, to generate said at least one subsequent frame in the color buffer, for being output to the display panel and displayed on the display panel.