diff --git a/rust/ql/lib/codeql/rust/internal/typeinference/DerefChain.qll b/rust/ql/lib/codeql/rust/internal/typeinference/DerefChain.qll
index 5c40f623f170..f71bb093c3b7 100644
--- a/rust/ql/lib/codeql/rust/internal/typeinference/DerefChain.qll
+++ b/rust/ql/lib/codeql/rust/internal/typeinference/DerefChain.qll
@@ -60,7 +60,10 @@ private module UnboundListInput implements UnboundListImpl::InputSig<Location> {
 
   class Element = DerefImplItemNode;
 
-  int getId(Element e) { idOfRaw(Synth::convertAstNodeToRaw(e), result) }
+  int getId(Element e) {
+    CachedStage::ref() and
+    idOfRaw(Synth::convertAstNodeToRaw(e), result)
+  }
 
   string getElementString(Element e) { result = e.resolveSelfTy().getName() }
 
diff --git a/rust/ql/lib/codeql/rust/internal/typeinference/TypeInference.qll b/rust/ql/lib/codeql/rust/internal/typeinference/TypeInference.qll
index d591c947e124..a6d0859ce475 100644
--- a/rust/ql/lib/codeql/rust/internal/typeinference/TypeInference.qll
+++ b/rust/ql/lib/codeql/rust/internal/typeinference/TypeInference.qll
@@ -36,6 +36,7 @@ private module Input1 implements InputSig1<Location> {
   class TypeAbstraction = TA::TypeAbstraction;
 
   int getTypeParameterId(TypeParameter tp) {
+    CachedStage::ref() and
     tp =
       rank[result](TypeParameter tp0, int kind, int id1, int id2 |
         kind = 1 and
diff --git a/shared/util/codeql/util/UnboundList.qll b/shared/util/codeql/util/UnboundList.qll
index 622895a6bd01..1d0ce06d7a82 100644
--- a/shared/util/codeql/util/UnboundList.qll
+++ b/shared/util/codeql/util/UnboundList.qll
@@ -52,6 +52,7 @@ module Make<LocationSig Location, InputSig<Location> Input> {
   /** Gets the rank of element `e`, which is used internally in the string encoding. */
   int getRank(Element e) { e = DenseRank<DenseRankInput>::denseRank(result) }
 
+  cached
   private string encode(Element e) { result = getRank(e).toString() }
 
   bindingset[s]