So far, the cross-sections used by the MORET code (developed by IRSN) could only be taken from external multi-group libraries. Then, it has been decided to plan new developments in MORET 5 to control the whole criticality calculation process, from the reading of nuclear data to the Monte Carlo simulation itself. The features related to this new version will allow to perform criticality calculations either with a multi-group or a continuous energy treatment based on different nuclear data evaluations. However, these improvements tend to increase simulation calculation times, in particular for non homogenized calculations. That is why some reflections were made in order to find various means to reduce the computing times. The purpose of this research is to study the feasibility and the efficiency of performing MORET 5 calculations with two types of optimized cross sections libraries: one for a very fine multi-group treatment and another for a universal continuous energy treatment. First results of the new Woodcock tracking implementation are also presented in this paper.