Backout bug 390244 due to tbox orange, per #developers

toolkit/components/places/src/nsNavHistory.cpp

@@ -3349,10 +3349,11 @@ nsNavHistory::PerformVacuumIfIdle()
       NS_ENSURE_SUCCESS(rv, rv);
     }
     else {
-      // if our database was created before incremental vacuuming
-      // do a full vacuum on idle
+#if 0
+      // Currently commented out because compression is very slow
       rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING("VACUUM;"));
       NS_ENSURE_SUCCESS(rv, rv);
+#endif
     }
   }
   return NS_OK;