New variable-speed drives with improved-design synchronous reluctance machines may now be capable of reaching high efficiency, even up to the IE4 level [1]. These machines have been studied for many years and significant progress was made in the 1990s using axial laminations in the rotor [2]. At that time, the technology was reviewed and identified, in principle, as a viable alternative [3]. However, the axially-laminated rotor machine can be very difficult to manufacture and more recent designs use radial laminations with ducts. This paper brings further contributions by introducing new global performance indices and proposes a systematic optimization method for practical design. This establishes natural limitations of the machine when employing topologies that can be manufactured in high volumes and available high-performance materials.