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 12609)
+++ src/org/openstreetmap/josm/actions/SimplifyWayAction.java	(revision )
@@ -208,11 +208,14 @@
             }
         }
 
-        Set<Node> delNodes = new HashSet<>();
-        delNodes.addAll(w.getNodes());
-        delNodes.removeAll(newNodes);
+        // workaround for slow AbstractSet.removeAll
+		Set<Node> delNodes = new HashSet<>(w.getNodes());
+		for (Node n : newNodes) {
+			delNodes.remove(n);
+		}
+
 
-        if (delNodes.isEmpty()) return null;
+		if (delNodes.isEmpty()) return null;
 
         Collection<Command> cmds = new LinkedList<>();
         Way newWay = new Way(w);