diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 4ca878a1be0da..59dc369fe17f7 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -141,6 +141,7 @@ struct LoweringContext<'a, 'hir> {
     /// NodeIds of pattern identifiers and labelled nodes that are lowered inside the current HIR owner.
     ident_and_label_to_local_id: NodeMap<hir::ItemLocalId>,
     /// NodeIds that are lowered inside the current HIR owner. Only used for duplicate lowering check.
+    #[cfg(debug_assertions)]
     node_id_to_local_id: NodeMap<hir::ItemLocalId>,
 
     allow_try_trait: Lrc<[Symbol]>,
@@ -172,6 +173,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             current_def_id_parent: CRATE_DEF_ID,
             item_local_id_counter: hir::ItemLocalId::ZERO,
             ident_and_label_to_local_id: Default::default(),
+            #[cfg(debug_assertions)]
             node_id_to_local_id: Default::default(),
             trait_map: Default::default(),
 
@@ -591,6 +593,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let current_bodies = std::mem::take(&mut self.bodies);
         let current_ident_and_label_to_local_id =
             std::mem::take(&mut self.ident_and_label_to_local_id);
+
+        #[cfg(debug_assertions)]
         let current_node_id_to_local_id = std::mem::take(&mut self.node_id_to_local_id);
         let current_trait_map = std::mem::take(&mut self.trait_map);
         let current_owner =
@@ -605,8 +609,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         // and the caller to refer to some of the subdefinitions' nodes' `LocalDefId`s.
 
         // Always allocate the first `HirId` for the owner itself.
-        let _old = self.node_id_to_local_id.insert(owner, hir::ItemLocalId::ZERO);
-        debug_assert_eq!(_old, None);
+        #[cfg(debug_assertions)]
+        {
+            let _old = self.node_id_to_local_id.insert(owner, hir::ItemLocalId::ZERO);
+            debug_assert_eq!(_old, None);
+        }
 
         let item = self.with_def_id_parent(def_id, f);
         debug_assert_eq!(def_id, item.def_id().def_id);
@@ -618,7 +625,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         self.attrs = current_attrs;
         self.bodies = current_bodies;
         self.ident_and_label_to_local_id = current_ident_and_label_to_local_id;
-        self.node_id_to_local_id = current_node_id_to_local_id;
+
+        #[cfg(debug_assertions)]
+        {
+            self.node_id_to_local_id = current_node_id_to_local_id;
+        }
         self.trait_map = current_trait_map;
         self.current_hir_id_owner = current_owner;
         self.item_local_id_counter = current_local_counter;
diff --git a/compiler/rustc_ast_lowering/src/pat.rs b/compiler/rustc_ast_lowering/src/pat.rs
index 59c0e24479a09..ace7bfb5c73f2 100644
--- a/compiler/rustc_ast_lowering/src/pat.rs
+++ b/compiler/rustc_ast_lowering/src/pat.rs
@@ -264,18 +264,24 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         match self.resolver.get_partial_res(p.id).map(|d| d.expect_full_res()) {
             // `None` can occur in body-less function signatures
             res @ (None | Some(Res::Local(_))) => {
-                let canonical_id = match res {
-                    Some(Res::Local(id)) => id,
-                    _ => p.id,
-                };
-                // All identifiers resolves to this canonical identifier share its `HirId`.
-                let binding_id = if canonical_id == p.id {
-                    self.ident_and_label_to_local_id.insert(canonical_id, hir_id.local_id);
-                    hir_id
-                } else {
-                    hir::HirId {
-                        owner: self.current_hir_id_owner,
-                        local_id: self.ident_and_label_to_local_id[&canonical_id],
+                let binding_id = match res {
+                    Some(Res::Local(id)) => {
+                        // In `Or` patterns like `VariantA(s) | VariantB(s, _)`, multiple identifier patterns
+                        // will be resolved to the same `Res::Local`. Thus they just share a single
+                        // `HirId`.
+                        if id == p.id {
+                            self.ident_and_label_to_local_id.insert(id, hir_id.local_id);
+                            hir_id
+                        } else {
+                            hir::HirId {
+                                owner: self.current_hir_id_owner,
+                                local_id: self.ident_and_label_to_local_id[&id],
+                            }
+                        }
+                    }
+                    _ => {
+                        self.ident_and_label_to_local_id.insert(p.id, hir_id.local_id);
+                        hir_id
                     }
                 };
                 hir::PatKind::Binding(