Improve perf with some benchmarking.

Re translate change see http://jsperf.com/coerce-vs-join-array

js/id/behavior/hover.js

@@ -7,18 +7,20 @@
    Only one of these elements can have the :hover pseudo-class, but all of them will
    have the .hover class.
  */
-iD.behavior.Hover = function () {
+iD.behavior.Hover = function() {
     var hover = function(selection) {
         selection.classed('behavior-hover', true);
 
-        selection.on('mouseover.hover', function () {
+        function mouseover() {
             var datum = d3.event.target.__data__;
             if (datum) {
                 selection.selectAll('*')
                     .filter(function (d) { return d === datum; })
                     .classed('hover', true);
             }
-        });
+        }
+
+        selection.on('mouseover.hover', mouseover);
 
         selection.on('mouseout.hover', function () {
             selection.selectAll('.hover')

js/id/graph/node.js

@@ -12,7 +12,7 @@ _.extend(iD.Node.prototype, {
     type: "node",
 
     extent: function() {
-        return iD.geo.Extent(this.loc);
+        return new iD.geo.Extent(this.loc);
     },
 
     geometry: function(graph) {

js/id/renderer/map.js

@@ -301,7 +301,7 @@ iD.Map = function(context) {
 
     map.extent = function(_) {
         if (!arguments.length) {
-            return iD.geo.Extent(projection.invert([0, dimensions[1]]),
+            return new iD.geo.Extent(projection.invert([0, dimensions[1]]),
                                  projection.invert([dimensions[0], 0]));
         } else {
             var extent = iD.geo.Extent(_),

js/id/svg.js

@@ -7,7 +7,7 @@ iD.svg = {
 
     PointTransform: function(projection) {
         return function(entity) {
-            return 'translate(' + projection(entity.loc) + ')';
+            return 'translate(' + projection(entity.loc).join(',') + ')';
         };
     },
 

js/id/ui/lasso.js

@@ -22,7 +22,7 @@ iD.ui.lasso = function() {
     // top-left
     function topLeft(d) {
         return 'translate(' +
-            [Math.min(d[0][0], d[1][0]), Math.min(d[0][1], d[1][1])] + ')';
+            [Math.min(d[0][0], d[1][0]), Math.min(d[0][1], d[1][1])].join(',') + ')';
     }
 
     function width(d) { return Math.abs(d[0][0] - d[1][0]); }