The internet gives individuals access to learning through online technologies. The prolific use of Learning Management Systems (LMSs) in higher education institutions makes Information and Communication Technology (ICT) skills or e-skills very important. ICT skill levels have been positively related to students' effectiveness and efficiency in using LMSs. The purpose of this study was to examine the relationship between digital proficiency and user performance of students studying End User Computing when using the LMS at the University of South Africa (Unisa), an open distance learning institution. Based on their performance in a simulated competence-based assessment, students were categorized into four groups of a digital proficiency framework, namely Digital Awareness, Digital Literacy, Digital Competence and Digital Expertise. Students then used the LMS in a Human Computer Interaction (HCI) laboratory to perform three assigned tasks while eye tracking and usability testing data were collected. This evidence, including heat maps and gaze plots, was used to identify usability problems that the students experienced when using the LMS. The usability problems were then compared across the four digital proficiency groups to examine the relationship between students' digital proficiency and their performance in using the LMS. The findings show that the efficiency and effectiveness of using the LMS relate directly to students' proficiency levels. It is also clear that while some usability problems, especially visibility and language problems, were experienced by participants across all four levels of digital proficiency, other usability problems were specific to students with lower digital proficiency levels.