This command stops the rendering of graphics when the client is not in the foreground (i.e.: switched to another program with, for example, alt-tab). Useful if you experience flickering of the application window you switched to because of the redrawing of the 3D world under it.
/stopinactivedisplay -- shows the current state (0 or 1)
/stopinactivedisplay 1 -- stops rendering when inactive
/stopinactivedisplay 0 -- allows rendering when inactive (default)