Design cognition, human information processing in design, has been studied for decades in order to understand creative behavior and improve the creativity of design outcomes. Comparing designers’ performance during different design tasks is challenging since data obtained from sketches and verbal protocols are unstructured. Furthermore, there is no established method to evaluate directly the effectiveness and efficiency of the transition from novice to expert designer. This study argued that designers’ cognitive load had an effect on designers’ performance, and therefore designers’ cognitive demands during design tasks should be considered in the evaluation of design outcomes. The concept of cognitive efficiency, describing the relationship between design outcomes and designers’ cognitive demands, was proposed and found to be related to expertise levels and design strategies. Designers’ cognitive processes were described quantitatively using information-based approaches from three different perspectives:​ the process of problem structuring, the complexity of cognitive actions, and the connections between design ideas. The quantitative measures were found to relate to cognitive efficiency and designers’ expertise levels. The quantitative measures make it possible to highlight where and when cognitive resources should be focused and which design behaviors should be encouraged to improve cognitive efficiency. Effective design strategies related to high cognitive efficiency were also identified. Explicit decomposition and the breadth-first control strategy were found to benefit problem structuring. Generating early design conjectures was related to high cognitive efficiency. The application of the systematic design method helped the designers to organize their design processes and effectively revisit and improve previous design ideas. These design strategies can be used for design education and design method comparison.