http://www.sgi.com/tech/openGL/mjk.xlib/subsection3_3_6.html (Silicon Surf Promotional CD, 01/1995)
OpenGL supports immediate mode rendering where commands can be generated on the fly and sent directly to the screen. Programmers should be aware that their OpenGL programs might be run indirectly. In this case, immediate mode rendering could require a great deal of overhead for transport to the X server and possibly across a network.
For this reason, OpenGL programmers should try to use display lists when possible to batch rendering commands. Since the display lists are stored in the server, executing a display list has minimal overhead compared to executing the same commands in the display list immediately.
Display lists are likely to have other advantages since OpenGL implementations are allowed to compile them for maximum performance. Be aware you can mix display lists and immediate mode rendering to achieve the best mix of performance and rendering flexibility.