Index: src/org/openstreetmap/josm/actions/SimplifyWayAction.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- src/org/openstreetmap/josm/actions/SimplifyWayAction.java	(revision 12618)
+++ src/org/openstreetmap/josm/actions/SimplifyWayAction.java	(revision )
@@ -279,10 +279,11 @@
     }
 
     private static double course(double lat1, double lon1, double lat2, double lon2) {
-        return Math.atan2(Math.sin(lon1 - lon2) * Math.cos(lat2), Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1)
-                * Math.cos(lat2) * Math.cos(lon1 - lon2))
-                % (2 * Math.PI);
+		final double cosLat2 = Math.cos(lat2);
+		return Math.atan2(Math.sin(lon1 - lon2) * cosLat2, Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1)
+                * cosLat2 * Math.cos(lon1 - lon2)) % (2 * Math.PI);
     }
+
 
     private static double xtd(double lat1, double lon1, double lat2, double lon2, double lat3, double lon3) {
         double distAD = dist(lat1, lon1, lat3, lon3);