The image forming apparatus comprises a determination unit configured to determine whether or not corresponding image data is cached in accordance with an instruction for generation of image data for the file stored in the memory, and an image processing unit configured to generate image data for the file in a case that the determination unit determines that the corresponding image data is not cached. The image forming apparatus controls to skip generation of image data by the image processing unit in a case that the instruction for generation of image data for the file is an instruction for an anticipation cache of image data for the file, and a file type of the file is a second type requiring, for generation of image data, a longer amount of time than a first type.