Time-Triggered Controller Area Network is widely accepted as a viable solution for real-time communication systems such as in-vehicle communications. However, although TTCAN has been designed to support both periodic and sporadic real-time messages, previous studies mostly focused on providing deterministic real-time guarantees for periodic messages while barely addressing the performance issue of sporadic messages. In this paper, we present an O(n2) scheduling algorithm that can minimize the maximum duration of exclusive windows occupied by periodic messages, thereby minimizing the worst-case scheduling delays experienced by sporadic messages.