1. A method for determining a resolution and rendering an image, comprising the steps of: (a) rendering a current image frame into a frame buffer at an image frame resolution; (b) computing a rendering time determined by how long it takes to render a previous image frame into said frame buffer; (c) comparing said rendering time to a high-water mark, wherein said high-water mark represents a second rendering time at which an image frame resolution would start to be reduced, and reducing said resolution for a next image frame, if said rendering time exceeds said high-water mark; and (d) comparing said rendering time to a low-water mark, wherein said low-water mark represents a third rendering time at which an image frame resolution would start to be increased, and expanding said resolution for a next image frame, if said rendering time is below said low-water mark and said image frame resolution does not equal a target resolution.