Research on Cognitive Load Theory has shown that measures of cognitive load can reveal important information about the cognitive consequences of instructional conditions that is not necessarily reflected by traditional performance-based measures. Although, the individual measures of cognitive load can be considered important to determine the power of different instructional conditions, a meaningful interpretation of a certain level of cognitive load can only be given in the context of its associated performance level, and vice versa. This was recognized by Paas and Van Merrienboer (1993) who developed a 2-dimensional computational approach to combine measures of test performance with measures of the associated mental effort in order to compare the 'mental efficiency' of instructional conditions. In this approach, high task performance associated with low effort is termed high instructional efficiency, whereas low task performance with high effort is termed low instructional efficiency. Here we explore the utility of employing multi-dimensional approaches, in particular two 2-dimensional efficiency measures and a new 3-dimensional approach, which combines the measures of learning effort, test effort and test performance. Each of these approaches with their associated insights and analyses may be useful for instructional researchers, e.g. as diagnostic instruments to identify different aspects of efficient or inefficient instructional conditions and can be implemented in a broad range of learning environments, including electronic environments, possibly enabling more effective learning-task selection.