The ARF layout is now an official plugin for Gephi. It can be directly installed by following Tools -> Plugins -> Available plugins. Then you need to select the ARF layout and click on Install.
When you select ARF from the layout menu, you will notice that ARF's parameters can be changed dynamically, while the layout is in progress. For large networks, one can adjust the Precision parameter to speed up the computation of the layout. You can initially set Precision to a larger number, e.g. 40-50, which will compute roughly a layout closer to the optimal layout. Afterwards, you can lower the Precision parameter to obtain a more precise computation of the layout.