Allen Jessup sent us a tip on using the Zoom command.  This is a nice function of the Zoom command hasn't been documented since the R12 manual. After initiating the Zoom command at the command line enter V for Vmax. This will cause AutoCAD to zoom out to the maximum area possible without a regeneration. In other words this will zoom you to the extents of your virtual screen. The virtual screen is the area of the drawing (database) coordinates that AutoCAD keeps the conversion to screen (pixel) coordinates in memory. Zooming out past this limit forces AutoCAD to re-compute the screen coordinates forcing a Regen.

Notes from Cadalyst Tip Patrol:  VMAX will zoom you to the outer most coordinates that have been used in a file.  It is different from Zoom Extents.  Zoom Extents will zoom out to where your further most objects are.