Portable or embedded systems as well as submicronic technologies have made the power consumption criterion crucial. Memory is known to be extremely power consuming. Moreover multimedia applications are memory intensive applications. Therefore, we propose new techniques to optimize a behavioral description of multimedia applications before the hardware/software partitioning (codesign). These transformations are performed on "for" loops that constitute the main parts which handle the arrays of the multimedia code. The paper presents an optimal algorithm to reduce the use of temporary arrays by loop fusion. Although the algorithm is not polynomial, experiments have shown that it is very efficient.