Previous research has shown that mindfulness is associated with slower passage of time in everyday life, and with lower self-reported time pressure. This study investigates some of the potential mechanisms behind these relationships. 318 participants submitted their responses to an online survey which collected data regarding passage of time judgments, time pressure, trait mindfulness, temperament, task load, and metacognitions about time. Using commonality and dominance analyses, we explored how these variables contributed, either alone or jointly, to predicting how fast (or slow) time seems to pass for participants, or how pressed for time they felt. Mindfulness and temperament had some overlaps in their ability to predict passage of time judgments and time pressure for durations at the month and 2-month scales. The temperamental trait of extraversion/surgency, as well as the Non-judging and Non-reacting facets of mindfulness were among the best predictors of passage of time judgments and time pressure. Attention-related variables were mainly related to time perception via their involvement in joint effects with other variables. Results also suggested that metacognitions about time interacted with other variables in predicting passage of time judgments, but only at the month scale. Finally, among all the variables included in this study, task load had the highest degree of involvement in predictions of self-reported time pressure at the week and month scales, but it contributed relatively little to predicting passage of time judgments. Results suggest that mindfulness relates to passage of time through its involvement in inferential processes. The data also shows how different factors are related to PoTJ at different time scales. Finally, results suggest the existence of both similarities and differences in how passage of time and time pressure relate to the other included variables.