Index: trunk/test/performance/org/openstreetmap/josm/data/osm/RoundingPerformanceTest.java
===================================================================
--- trunk/test/performance/org/openstreetmap/josm/data/osm/RoundingPerformanceTest.java	(revision 4573)
+++ trunk/test/performance/org/openstreetmap/josm/data/osm/RoundingPerformanceTest.java	(revision 4573)
@@ -0,0 +1,40 @@
+package org.openstreetmap.josm.data.osm;
+
+import org.junit.Test;
+import org.openstreetmap.josm.data.coor.LatLon;
+import org.openstreetmap.josm.data.coor.LatLonTest;
+
+import static org.junit.Assert.assertTrue;
+
+public class RoundingPerformanceTest extends LatLonTest {
+    
+    private static double oldRoundToOsmPrecision(double value) {
+        return Math.round(value / LatLon.MAX_SERVER_PRECISION) * LatLon.MAX_SERVER_PRECISION; // Old method, causes rounding errors, but efficient
+    }
+
+    @Test
+    public void test() {
+        final int n = 1000000;
+        long start = System.nanoTime();
+        for (int i = 0; i < n; i++) {
+            for (double value : sampleValues) {
+                oldRoundToOsmPrecision(value);
+            }
+        }
+        long end = System.nanoTime();
+        long oldTime = end-start;
+        System.out.println("Old time: "+oldTime/1000000.0 + " ms");
+        
+        start = System.nanoTime();
+        for (int i = 0; i < n; i++) {
+            for (double value : sampleValues) {
+                LatLon.roundToOsmPrecision(value);
+            }
+        }
+        end = System.nanoTime();
+        long newTime = end-start;
+        System.out.println("New time: "+newTime/1000000.0 + " ms");
+        
+        assertTrue(newTime <= oldTime*10);
+    }
+}