1. A system for optimizing character string output processing, comprising: an acquiring section for acquiring an output program, which sequentially executes a plurality of character string output instructions, and which outputs a text in which a plurality of output character strings are combined; a static converter for converting a character code set of a character string constant of at least one of the character string output instructions, each for outputting a character string constant, from a first code set for internal processing to a second code set for output, before execution of the output program; a first buffer for buffering values of two or more character string variables to be outputted respectively by two or more of the character string output instructions, without converting the character code set from the first code set, during the execution of the output program; a dynamic converter for collectively converting the values of the two or more character string variables which have been buffered by the first buffer, from the first code set to the second code set; and an output controller for allowing a character string constant, whose character code set has been converted by the static converter, and the values of the two or more character string variables, whose character code set has been converted by the dynamic converter, to be outputted as at least a part of the text.