1. A display control device comprising: processing circuitry configured to detect change of a screen; and execute, depending on change of the screen detected, both of (i) provisional update processing that generates predetermined matching result information based on a result of calculation on a previous frame displayed on the screen, searches the screen for a region similar to a specified image template by using the predetermined matching result information as part of a matching condition for a next frame, and performs overlay display of an icon in the similar region, and (ii) definitive update processing that searches for a region similar to the image template by using a matching condition larger than the predetermined matching result information, and performs overlay display of an icon at a position corresponding to the similar region, wherein the processing circuitry detects progress of a change event of the screen, the processing circuitry is further configured to execute the provisional update processing and the definitive update processing in parallel when the processing circuitry detects the change of the screen and during the progress of the change event of the screen, and in the provisional update processing, the matching result information is generated in next provisional update processing based on a position at which the icon is displayed in previous provisional update processing already executed and a result of calculation on the previous frame in the definitive update processing.