diff --git a/simgear/canvas/elements/CanvasMap.cxx b/simgear/canvas/elements/CanvasMap.cxx
index a7c43a51..ca97c4f7 100644
--- a/simgear/canvas/elements/CanvasMap.cxx
+++ b/simgear/canvas/elements/CanvasMap.cxx
@@ -97,17 +97,26 @@ namespace canvas
           || (!geo_node->isDirty() && !_projection_dirty) )
         continue;
 
-      GeoCoord lat = parseGeoCoord(geo_node->getLat());
-      if( lat.type != GeoCoord::LATITUDE )
-        continue;
-
-      GeoCoord lon = parseGeoCoord(geo_node->getLon());
-      if( lon.type != GeoCoord::LONGITUDE )
-        continue;
-
-      Projection::ScreenPosition pos =
-        _projection->worldToScreen(lat.value, lon.value);
-
+      double latD = -9999.0, lonD = -9999.0;
+      if (geo_node->isDirty()) {
+        GeoCoord lat = parseGeoCoord(geo_node->getLat());
+        if( lat.type != GeoCoord::LATITUDE )
+          continue;
+        
+        GeoCoord lon = parseGeoCoord(geo_node->getLon());
+        if( lon.type != GeoCoord::LONGITUDE )
+          continue;
+        
+        // save the parsed values so we can re-use them if only projection
+        // is changed (very common case for moving vehicle)
+        latD = lat.value;
+        lonD = lon.value;
+        geo_node->setCachedLatLon(std::make_pair(latD, lonD));
+      } else {
+        std::tie(latD, lonD) = geo_node->getCachedLatLon();
+      }
+      
+      Projection::ScreenPosition pos = _projection->worldToScreen(latD, lonD);
       geo_node->setScreenPos(pos.x, pos.y);
 
 //      geo_node->print();
diff --git a/simgear/canvas/elements/map/geo_node_pair.hxx b/simgear/canvas/elements/map/geo_node_pair.hxx
index 4733238b..aa01aa91 100644
--- a/simgear/canvas/elements/map/geo_node_pair.hxx
+++ b/simgear/canvas/elements/map/geo_node_pair.hxx
@@ -99,6 +99,12 @@ namespace canvas
         return _node_lon ? _node_lon->getStringValue() : "";
       }
 
+      void setCachedLatLon(const std::pair<double, double>& latLon)
+      { _cachedLatLon = latLon; }
+      
+      std::pair<double, double> getCachedLatLon()
+      { return _cachedLatLon; }
+      
       void setTargetName(const std::string& name)
       {
         _target_name = name;
@@ -138,6 +144,7 @@ namespace canvas
       std::string   _target_name;
       SGPropertyNode_ptr _xNode,
           _yNode;
+      std::pair<double, double> _cachedLatLon;
 
   };