1. A printer which, in analyzing a print job described in a printer control language, selects a language translation program corresponding to the printer control language and executes the language translation program on a memory, and carries out printing based on a result of analysis of the language translation program, the printer comprising: a use status computation section which collects statistics of a use status of the analyzed print job and computes a use frequency and an execution interval of the language translation program based on a result of the statistics; and a resident mode switching section which causes a language translation program with a highest use frequency to initially stay resident in the memory and further causing another language translation program with a high use frequency and a long execution interval to stay resident next to the language translation program with the highest use frequency in the memory.