diff --git a/ortools/routing/lp_scheduling.h b/ortools/routing/lp_scheduling.h
index 7176298e08..7e84b1eb4f 100644
--- a/ortools/routing/lp_scheduling.h
+++ b/ortools/routing/lp_scheduling.h
@@ -456,6 +456,9 @@ class RoutingCPSatWrapper : public RoutingLinearSolverWrapper {
     // significantly faster than both full presolve and no presolve.
     parameters_.set_cp_model_presolve(true);
     parameters_.set_max_presolve_iterations(1);
+    parameters_.set_cp_model_probing_level(0);
+    parameters_.set_use_sat_inprocessing(false);
+    parameters_.set_symmetry_level(0);
     parameters_.set_catch_sigint_signal(false);
     parameters_.set_mip_max_bound(1e8);
     parameters_.set_search_branching(sat::SatParameters::LP_SEARCH);
diff --git a/ortools/routing/routing.cc b/ortools/routing/routing.cc
index 36a04e11e3..bb0807493e 100644
--- a/ortools/routing/routing.cc
+++ b/ortools/routing/routing.cc
@@ -17,6 +17,7 @@
 
 #include <algorithm>
 #include <atomic>
+#include <cstddef>
 #include <cstdint>
 #include <cstdlib>
 #include <cstring>
@@ -4770,10 +4771,13 @@ void RoutingModel::CreateNeighborhoodOperators(
       CreateCPOperator<ExtendedSwapActiveOperator>();
   std::vector<std::vector<int64_t>> alternative_sets(disjunctions_.size());
   for (const RoutingModel::Disjunction& disjunction : disjunctions_) {
-    // Only add disjunctions of cardinality 1, as
+    // Only add disjunctions of cardinality 1 and of size > 1, as
     // SwapActiveToShortestPathOperator and TwoOptWithShortestPathOperator only
-    // support DAGs.
-    if (disjunction.value.max_cardinality == 1) {
+    // support DAGs, and don't care about chain-DAGS.
+    // TODO(user): Optimize TwoOptWithShortestPathOperator to skip DAG-less
+    // chains.
+    if (disjunction.value.max_cardinality == 1 &&
+        disjunction.indices.size() > 1) {
       alternative_sets.push_back(disjunction.indices);
     }
   }
@@ -4992,6 +4996,11 @@ LocalSearchOperator* RoutingModel::GetNeighborhoodOperators(
   CP_ROUTING_PUSH_OPERATOR(TWO_OPT, two_opt);
   CP_ROUTING_PUSH_OPERATOR(OR_OPT, or_opt);
   CP_ROUTING_PUSH_OPERATOR(RELOCATE_EXPENSIVE_CHAIN, relocate_expensive_chain);
+  size_t max_alternative_set_size = 0;
+  for (const RoutingModel::Disjunction& disjunction : disjunctions_) {
+    max_alternative_set_size =
+        std::max(max_alternative_set_size, disjunction.indices.size());
+  }
   if (!disjunctions_.empty()) {
     CP_ROUTING_PUSH_OPERATOR(MAKE_INACTIVE, make_inactive);
     CP_ROUTING_PUSH_OPERATOR(MAKE_CHAIN_INACTIVE, make_chain_inactive);
@@ -5007,9 +5016,11 @@ LocalSearchOperator* RoutingModel::GetNeighborhoodOperators(
     CP_ROUTING_PUSH_OPERATOR(SWAP_ACTIVE, swap_active);
     CP_ROUTING_PUSH_OPERATOR(SWAP_ACTIVE_CHAIN, swap_active_chain);
     CP_ROUTING_PUSH_OPERATOR(EXTENDED_SWAP_ACTIVE, extended_swap_active);
-    CP_ROUTING_PUSH_OPERATOR(SHORTEST_PATH_SWAP_ACTIVE,
-                             shortest_path_swap_active);
-    CP_ROUTING_PUSH_OPERATOR(SHORTEST_PATH_TWO_OPT, shortest_path_two_opt);
+    if (max_alternative_set_size > 1) {
+      CP_ROUTING_PUSH_OPERATOR(SHORTEST_PATH_SWAP_ACTIVE,
+                               shortest_path_swap_active);
+      CP_ROUTING_PUSH_OPERATOR(SHORTEST_PATH_TWO_OPT, shortest_path_two_opt);
+    }
   }
   LocalSearchOperator* main_operator_group =
       ConcatenateOperators(search_parameters, operators);