1. A portable electronic device, comprising: a touch screen display; one or more processors; memory; and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for: down sampling data for a graphical object to a first resolution; displaying the graphical object on the touch screen display using the down sampled data; while displaying the graphical object on the touch screen display using the down sampled data, detecting a multi-touch input associated with the graphical object; determining, based on the multi-touch input, an operation to be performed on the graphical object; performing the operation on the graphical object; while performing the operation on the graphical object, displaying changes to the graphical object caused by the operation in real time using the down sampled data; and, replacing the display of the graphical object using the down sampled data with a display of the graphical object with resampled data at a second resolution, higher than the first resolution.