Rendering and animating in real-time a multitude of articulated characters presents a real challenge, and few hardware systems are up to the task. Up to now, little research has been conducted to tackle the issue of real-time rendering of numerous virtual humans. This paper presents a hardware-independent technique that improves the display rate of animated characters by acting on the sole geometric and rendering information. We first review the acceleration techniques traditionally in use in computer graphics and highlight their suitability to articulated characters. We then show how impostors can be used to render virtual humans. We introduce concrete case studies that demonstrate the effectiveness of our approach. Finally, we tackle the visibility issue