Learning analytics dashboards are becoming increasingly common tools for providing feedback to learners. However, there is limited empirical evidence regarding the effects of learning analytics dashboard design features on learners' cognitive load, particularly in digital learning environments. To address this gap, we developed goal-based, explanatory, and instructional learning analytics dashboards in authentic online courses based on cognitive load theory, and evaluated the effects of the three information designs on cognitive load and performance. The study adopted a quasi-experimental approach over a semester-long course, involving 93 learners divided into four groups, each provided with differently designed information on their learning analytics dashboard. The results show that the incorporation of goals, explanations, and instructional information as support elements in the learning analytics dashboard did not have a significant impact on learners' cognitive load and performance. Both cognitive load and learning performance results were consistent and mutually validating. Additionally, the study found that compared to a control group without additional information, the group using the explanatory dashboard experienced an increase in germane cognitive load, and evidenced the effectiveness of explanatory information design. Overall, this study provides important insights for the enhancement and practical design of learning analytics dashboards and feedback methods.