1. A server device which receives a control instruction transmitted from a terminal device via a network and generates and transmits image data to be displayed on the terminal device in accordance with the received control instruction, comprising: a storage unit configured to store a set of the control instruction, an application program serving as an object of operation with the control instruction, and a thinning processing method for the control instruction associated with one another; a reception unit configured to receive a plurality of the control instructions transmitted from the terminal device; a thinning processing unit configured to, if an object of operation with the control instructions received by the reception unit is the application program in one of the set stored in the storage unit in association with the control instruction, execute thinning processing for the plurality of control instructions received using the thinning processing method in the one of the set stored in association with the control instruction; an image data generation unit configured to generate the image data to be displayed on the terminal device in accordance with the control instructions after the thinning processing; and a transmission unit configured to transmit the generated image data to the terminal device.