Index: /issm/trunk-jpl/src/m/plot/plot_overlay.js
===================================================================
--- /issm/trunk-jpl/src/m/plot/plot_overlay.js	(revision 20471)
+++ /issm/trunk-jpl/src/m/plot/plot_overlay.js	(revision 20472)
@@ -132,5 +132,8 @@
 		element = [elements[i][0] - 1, elements[i][1] - 1, elements[i][2] - 1];
 		if (element[0] in nanindices || element[1] in nanindices || element[2] in nanindices) continue;
-		indices = indices.concat(element);
+		indices[indices.length] = element[0];
+		indices[indices.length] = element[1];
+		indices[indices.length] = element[2];
+
 	}
 	indices.itemSize = 1;