Zooming specific WMS using OpenLayers 2?

Question

I'm looking for a way to use multiple WMS on my application. If a user zooms in/out another baselayer is supposed to be selected. As for now, I've come across the following:

map.events.on({ "zoomend": function (e) {
    if (this.getZoom() > 10) {
      mapnik.setVisibility(false);
      layertest.setVisibility(true);
    }
    else {
      layertest.setVisibility(false);
      mapnik.setVisibility(true);
         }
                                        }
            });

The problem I still encounter is really bad performance. Well it works, but is there maybe a faster way of doing this?