The Limited Attentional Capacity Model (LACM) greatly influences the memory processing system, causing a trade-off relationship between the levels of complexity, accuracy, and fluency (CAF) in the writing of English as a foreign language (EFL) by student writers. For example, when engaged in the development of accuracy in writing, students may produce less complicated sentence patterns or less fluent sentences, and vice versa. Among the factors influencing EFL student writers’ use of LACM and their ability to maintain a balanced shifting relationship in CAF, time is considered one of the most influential variables. However, current literature on the influence of time factors in Taiwanese EFL college students’ writing performance in CAF is rather limited. To shed light on this subject, the researchers of this study investigated 42 EFL students’ writing samples that were produced under two different time frames (20 minutes versus 40 minutes). Both inferential and descriptive statistics were employed to analyze the data collected from the participants’ textual output. The research results indicate a clear trade-off model triggered by time factors between fluency and complexity/accuracy. Specifically, when writing under great pressure (i.e. limited time frame of 20 minutes), the participants tended to develop writing fluency over complexity and accuracy. In contrast, students’ writing complexity and accuracy were developed at the expense of fluency when they were given more time (i.e. 40 minutes).