Index: /trunk/src/org/openstreetmap/josm/gui/dialogs/SelectionListDialog.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/dialogs/SelectionListDialog.java	(revision 5712)
+++ /trunk/src/org/openstreetmap/josm/gui/dialogs/SelectionListDialog.java	(revision 5713)
@@ -74,4 +74,5 @@
 import org.openstreetmap.josm.tools.InputMapUtils;
 import org.openstreetmap.josm.tools.Shortcut;
+import org.openstreetmap.josm.tools.SubclassFilteredCollection;
 
 /**
@@ -590,8 +591,11 @@
             remember(selection);
             double dist = -1;
-            if(this.selection.size() == 1) {
-                OsmPrimitive o = this.selection.get(0);
-                if(o instanceof Way)
-                   dist = ((Way)o).getLength();
+            SubclassFilteredCollection<OsmPrimitive, Way> ways = new SubclassFilteredCollection<OsmPrimitive, Way>(selection, OsmPrimitive.wayPredicate);
+            // Compute total length of selected way(s) until an arbitrary limit set to 250 ways
+            // in order to prevent performance issue if a large number of ways are selected (old behaviour kept in that case, see #8403)
+            if (!ways.isEmpty() && ways.size() < 250) {
+                for (Way w : ways) {
+                    dist += w.getLength();
+                }
             }
             Main.map.statusLine.setDist(dist);