Optimize "OFS.ObjectManager.__contains__" method

CHANGES.rst

@@ -48,6 +48,9 @@ Bugs Fixed
 Features Added
 ++++++++++++++
 
+- Optimized the `OFS.ObjectManager.__contains__` method to do the
+  least amount of work necessary.
+
 - Optimized the `OFS.Traversable.getPhysicalPath` method to avoid excessive
   amounts of method calls.
 

src/OFS/ObjectManager.py

@@ -781,7 +781,11 @@ class ObjectManager(CopyContainer,
         return self._setObject(key, value)
 
     def __contains__(self, name):
-        return name in self.objectIds()
+        for ob in self._objects:
+            if name == ob['id']:
+                return True
+
+        return False
 
     def __iter__(self):
         return iter(self.objectIds())