A method, executed by a computer, of rendering image frames for a videogame, comprising the steps of: for a plurality of predetermined features of a virtual environment of a videogame, setting (s210) a respective per-frame movement distance threshold; calculating (s220) a respective minimum frame rate at which movement of each predetermined feature of the virtual environment of the videogame between successive image frames remains within the respective movement distance threshold; detecting (s230) whether the current frame rate is below one or more of the respective minimum frame rates; and if so, reducing (s240) a rendering resolution used during rendering of one or more subsequent image frames to increase the frame rate above one or more of the minimum frame rates, characterised in that the step of detecting whether the current frame rate is below one or more of the respective minimum frame rates comprises the steps of: determining whether the current frame rate is below the respective minimum frame rates of a threshold proportion of predetermined features for which a respective minimum frame rate is calculated; and if so, reducing a rendering resolution used during rendering of one or more subsequent image frames to increase the frame rate above the respective minimum frame rates for at least the threshold proportion of predetermined features for which a respective minimum frame rate is calculated. for a plurality of predetermined features of a virtual environment of a videogame, setting (s210) a respective per-frame movement distance threshold; calculating (s220) a respective minimum frame rate at which movement of each predetermined feature of the virtual environment of the videogame between successive image frames remains within the respective movement distance threshold; detecting (s230) whether the current frame rate is below one or more of the respective minimum frame rates; and if so, reducing (s240) a rendering resolution used during rendering of one or more subsequent image frames to increase the frame rate above one or more of the minimum frame rates, characterised in that the step of detecting whether the current frame rate is below one or more of the respective minimum frame rates comprises the steps of: determining whether the current frame rate is below the respective minimum frame rates of a threshold proportion of predetermined features for which a respective minimum frame rate is calculated; and if so, reducing a rendering resolution used during rendering of one or more subsequent image frames to increase the frame rate above the respective minimum frame rates for at least the threshold proportion of predetermined features for which a respective minimum frame rate is calculated. determining whether the current frame rate is below the respective minimum frame rates of a threshold proportion of predetermined features for which a respective minimum frame rate is calculated; and if so, reducing a rendering resolution used during rendering of one or more subsequent image frames to increase the frame rate above the respective minimum frame rates for at least the threshold proportion of predetermined features for which a respective minimum frame rate is calculated. <EOS>