Kahneman's dual-process model postulates that two systems are involved in decision-making: slow thinking, defined as analytical processing of information, and fast thinking, where decisions emerge from intuitive, automatic responses. Climbers in Olympic bouldering typically engage in slow thinking to interpret movements and explore climbing strategies. However, time constraints imposed by regulations, combined with ineffective decision-making and failed climbing attempts, may compel them to make more intuitive, fast decisions. This study examined climbers' decision-making and bouldering performance under varying time constraints. A total of 48 elite climbers were asked to climb three boulders, each within a different timeframe: four, two, and one minute. Data collection included boulder previewing times, appropriateness of decision-making, completed boulders, climbing attempts, and climbing times. Findings revealed that, as time constraints increased, absolute previewing time decreased, while previewing ratio relative to given time increased. Climbers made better decisions, did more attempts, had longer total climbing times, and were more successful when given time was longer, while relative climbing time increased when time was lower. Findings indicate that increased time constraints negatively affected climbers' strategic behaviour and bouldering performance. This decline in decision-making and performance may be attributed to less time for slow thinking and actual climbing.