diff --git a/code/map_data_render.js b/code/map_data_render.js
index 4a21f7c9..3bd12e50 100644
--- a/code/map_data_render.js
+++ b/code/map_data_render.js
@@ -14,14 +14,12 @@ window.Render = function() {
   // under the portals
   this.LINK_VISIBLE_PIXEL_LENGTH = this.CLUSTER_SIZE;
 
-  this.entityVisibilityZoom = undefined;
-
   this.portalMarkerScale = undefined;
 }
 
 
 // start a render pass. called as we start to make the batch of data requests to the servers
-window.Render.prototype.startRenderPass = function() {
+window.Render.prototype.startRenderPass = function(level,bounds) {
   this.isRendering = true;
 
   this.deletedGuid = {};  // object - represents the set of all deleted game entity GUIDs seen in a render pass
@@ -29,6 +27,16 @@ window.Render.prototype.startRenderPass = function() {
   this.seenPortalsGuid = {};
   this.seenLinksGuid = {};
   this.seenFieldsGuid = {};
+
+  this.bounds = bounds;
+
+  this.clearPortalsBelowLevel(level);
+
+  this.resetPortalClusters();
+  this.resetLinkVisibility();
+
+  this.rescalePortalMarkers();
+
 }
 
 window.Render.prototype.clearPortalsBelowLevel = function(level) {
@@ -44,40 +52,6 @@ window.Render.prototype.clearPortalsBelowLevel = function(level) {
   console.log('Render: deleted '+count+' portals by level');
 }
 
-window.Render.prototype.clearEntitiesOutsideBounds = function(bounds) {
-  var pcount=0, lcount=0, fcount=0;
-
-  for (var guid in window.portals) {
-    var p = portals[guid];
-    if (!bounds.contains (p.getLatLng()) && guid !== selectedPortal && !artifact.isInterestingPortal(guid)) {
-      this.deletePortalEntity(guid);
-      pcount++;
-    }
-  }
-
-  for (var guid in window.links) {
-    var l = links[guid];
-    if (!bounds.intersects (l.getBounds())) {
-      this.deleteLinkEntity(guid);
-      lcount++;
-    }
-  }
-
-  for (var guid in window.fields) {
-    var f = fields[guid];
-    if (!bounds.intersects (f.getBounds())) {
-      this.deleteFieldEntity(guid);
-      fcount++;
-    }
-  }
-  console.log('Render: deleted '+pcount+' portals, '+lcount+' links, '+fcount+' fields by bounds check');
-}
-
-// TODO? as well as clearing portals by level, and clearing entities outside the bounds...
-// can we clear unneeded 'fake' links after zooming out? based on the portals no longer being available to construct
-// the data? (not *required* - as they'll be removed in the endRenderPass code - but clearing things earlier rather than
-// later is preferred, if possible)
-
 
 // process deleted entity list and entity data
 window.Render.prototype.processTileData = function(tiledata) {
@@ -406,21 +380,15 @@ window.Render.prototype.createLinkEntity = function(ent,faked) {
 
 
 
-window.Render.prototype.updateEntityVisibility = function() {
-  if (this.entityVisibilityZoom === undefined || this.entityVisibilityZoom != map.getZoom()) {
-    this.entityVisibilityZoom = map.getZoom();
+window.Render.prototype.rescalePortalMarkers = function() {
+  if (this.portalMarkerScale === undefined || this.portalMarkerScale != portalMarkerScale()) {
+    this.portalMarkerScale = portalMarkerScale();
 
-    this.resetPortalClusters();
-    this.resetLinkVisibility();
+    console.log('Render: map zoom '+map.getZoom()+' changes portal scale to '+portalMarkerScale()+' - redrawing all portals');
 
-    if (this.portalMarkerScale === undefined || this.portalMarkerScale != portalMarkerScale()) {
-      this.portalMarkerScale = portalMarkerScale();
-
-      console.log('Render: map zoom '+map.getZoom()+' changes portal scale to '+portalMarkerScale()+' - redrawing all portals');
-
-      //NOTE: we're not calling this because it resets highlights - we're calling it as it resets the style (inc size) of all portal markers
-      resetHighlightedPortals();
-    }
+    //NOTE: we're not calling this because it resets highlights - we're calling it as it
+    // resets the style (inc size) of all portal markers, applying the new scale
+    resetHighlightedPortals();
   }
 }
 
@@ -458,7 +426,7 @@ window.Render.prototype.resetPortalClusters = function() {
       var guid = c[i];
       var p = window.portals[guid];
       var layerGroup = portalsFactionLayers[parseInt(p.options.level)][p.options.team];
-      if (i<this.CLUSTER_PORTAL_LIMIT || p.options.guid == selectedPortal || artifact.isInterestingPortal(p.options.guid)) {
+      if ((i<this.CLUSTER_PORTAL_LIMIT || p.options.guid == selectedPortal || artifact.isInterestingPortal(p.options.guid)) && this.bounds.contains(p.getLatLng())) {
         if (!layerGroup.hasLayer(p)) {
           layerGroup.addLayer(p);
         }
@@ -485,7 +453,9 @@ window.Render.prototype.addPortalToMapLayer = function(portal) {
   // however, it won't make a lot of visible difference compared to just pushing to the end of the list, then
   // adding to the visible layer if the list is below the limit
   if (this.portalClusters[cid].length < this.CLUSTER_PORTAL_LIMIT || portal.options.guid == selectedPortal || artifact.isInterestingPortal(portal.options.guid)) {
-    portalsFactionLayers[parseInt(portal.options.level)][portal.options.team].addLayer(portal);
+    if (this.bounds.contains(portal.getLatLng())) {
+      portalsFactionLayers[parseInt(portal.options.level)][portal.options.team].addLayer(portal);
+    }
   }
 }
 
@@ -501,7 +471,7 @@ window.Render.prototype.removePortalFromMapLayer = function(portal) {
     var index = this.portalClusters[cid].indexOf(portal.options.guid);
     if (index >= 0) {
       this.portalClusters[cid].splice(index,1);
-      // FIXME? if this portal was in on the screen (in the first 10), and we still have 10+ portals, add the new 10to to the screen?
+      // FIXME? if this portal was in on the screen (in the first 10), and we still have 10+ portals, add the new 10th to the screen?
     }
   }
 }
@@ -520,6 +490,10 @@ window.Render.prototype.getPortalClusterID = function(portal) {
 
 
 window.Render.prototype.linkVisible = function(link) {
+  if (!this.bounds.intersects(link.getBounds())) {
+    return false;
+  }
+
   var lengthSquared = this.getLinkPixelLengthSquared (link);
 
   return lengthSquared >= this.LINK_VISIBLE_PIXEL_LENGTH*this.LINK_VISIBLE_PIXEL_LENGTH;
diff --git a/code/map_data_request.js b/code/map_data_request.js
index 25746ddd..0fac9c92 100644
--- a/code/map_data_request.js
+++ b/code/map_data_request.js
@@ -227,11 +227,8 @@ window.MapDataRequest.prototype.refresh = function() {
 
   window.runHooks ('mapDataRefreshStart', {bounds: bounds, mapZoom: mapZoom, dataZoom: dataZoom, minPortalLevel: tileParams.level, tileBounds: dataBounds});
 
-  this.render.startRenderPass();
-  this.render.clearPortalsBelowLevel(tileParams.level);
-  this.render.clearEntitiesOutsideBounds(dataBounds);
+  this.render.startRenderPass(tileParams.level, dataBounds);
 
-  this.render.updateEntityVisibility();
 
   this.render.processGameEntities(artifact.getArtifactEntities());