An image forming apparatus according to the present invention performs image processing on image data in units of pages stored in a page memory on the basis of parameter setting, transferring the image data to a buffer at a first speed, transmitting the image data, which is read out from the buffer at a second speed, to an image forming unit, and executing parameter setting for image processing performed when image data for a subsequent page is transferred after the image data for a single page has been transferred but before image data for the subsequent page is started to be transferred, wherein the first speed is faster than a second speed.