Pedestrian studies in retail areas are critical for comfort and convenience in transportation facility designs. But existing literature lacks detailed empirical observations that focus on pedestrian speed variations and their mechanisms in front of stores. This paper bridges this gap by analyzing 1193 pedestrian trajectories in front of a convenience store located in a metro station. The results show that the store imposes a non-uniform slowing effect on the pedestrian flow. The spatial distribution and the lower walking speed of consumers and gazing pedestrians jointly contribute to such an effect while avoiding behaviors between pedestrians play little role. The findings complement the existing empirical observations and lay a foundation for realistic pedestrian modeling in retail areas.