To successfully learn using freely available (and non-curated) Internet resources, university students need to search for, critically evaluate and select online information, and verify sources (defined as Critical Online Reasoning, COR). Recent research indicates substantial deficits in COR skills among higher education students. To support students in learning how to critically use online information for their learning, it is necessary to better understand the strategies and practices that might elicit less critically-reflective judgments about online information and thus account for such deficits. To this end, using eye tracking data, we investigate how the COR behaviors of students who critically-reflectively evaluate the credibility of online information ('high performers') differ from those of students who do not critically-reflectively evaluate it ('low performers'): 19 students were divided into high and low performers according to their performance in the newly developed Critical Online Reasoning Assessment (CORA). The fixation and dwell times of both groups during CORA task processing were compared regarding time spent on the different processing steps and eye movements on the visited web pages. The results show noticeable differences between the two groups, indicating that low performers indeed approached the task rather heuristically than systematically, and that COR skills require targeted and effective training in higher education.