diff --git a/src/Func.cpp b/src/Func.cpp
index a4a9363494dd..a17bc3ee4057 100644
--- a/src/Func.cpp
+++ b/src/Func.cpp
@@ -624,13 +624,6 @@ Func Stage::rfactor(const RVar &r, const Var &v) {
 // Helpers for rfactor implementation
 namespace {
 
-optional<RVar> find_rvar(const vector<RVar> &items, const Dim &dim) {
-    const auto has_v = std::find_if(items.begin(), items.end(), [&](auto &x) {
-        return dim_match(dim, x);
-    });
-    return has_v == items.end() ? std::nullopt : std::make_optional(*has_v);
-}
-
 optional<Dim> find_dim(const vector<Dim> &items, const VarOrRVar &v) {
     const auto has_v = std::find_if(items.begin(), items.end(), [&](auto &x) {
         return dim_match(x, v);
@@ -841,6 +834,7 @@ Func Stage::rfactor(const vector<pair<RVar, Var>> &preserved) {
     vector<RVar> preserved_rvars;
     vector<Var> preserved_vars;
     vector<Dim> preserved_rdims;
+    unordered_set<string> preserved_rdims_set;
     vector<Dim> intermediate_rdims;
     {
         unordered_map<string, int> dim_ordering;
@@ -848,14 +842,15 @@ Func Stage::rfactor(const vector<pair<RVar, Var>> &preserved) {
             dim_ordering.emplace(definition.schedule().dims()[i].var, i);
         }
 
-        vector<tuple<RVar, Var, Dim>> preserved_with_dims;
+        using PreservedData = tuple<RVar, Var, Dim>;
+        vector<PreservedData> preserved_with_dims;
         for (const auto &[rv, v] : preserved) {
             const optional<Dim> rdim = find_dim(definition.schedule().dims(), rv);
             internal_assert(rdim);
             preserved_with_dims.emplace_back(rv, v, *rdim);
         }
 
-        std::sort(preserved_with_dims.begin(), preserved_with_dims.end(), [&](const auto &lhs, const auto &rhs) {
+        std::sort(preserved_with_dims.begin(), preserved_with_dims.end(), [&](const PreservedData &lhs, const PreservedData &rhs) {
             return dim_ordering.at(std::get<2>(lhs).var) < dim_ordering.at(std::get<2>(rhs).var);
         });
 
@@ -863,10 +858,11 @@ Func Stage::rfactor(const vector<pair<RVar, Var>> &preserved) {
             preserved_rvars.push_back(rv);
             preserved_vars.push_back(v);
             preserved_rdims.push_back(dim);
+            preserved_rdims_set.insert(dim.var);
         }
 
         for (const Dim &dim : definition.schedule().dims()) {
-            if (dim.is_rvar() && !find_rvar(preserved_rvars, dim)) {
+            if (dim.is_rvar() && !preserved_rdims_set.count(dim.var)) {
                 intermediate_rdims.push_back(dim);
             }
         }
@@ -971,14 +967,9 @@ Func Stage::rfactor(const vector<pair<RVar, Var>> &preserved) {
 
         vector<Dim> reducing_dims;
         {
-            unordered_set<string> preserved_rdim_set;
-            for (const auto &dim : preserved_rdims) {
-                preserved_rdim_set.insert(dim.var);
-            }
-
             // Remove rvar dims NOT IN the preserved list from the REDUCING Func
             for (const auto &dim : definition.schedule().dims()) {
-                if (!dim.is_rvar() || preserved_rdim_set.count(dim.var)) {
+                if (!dim.is_rvar() || preserved_rdims_set.count(dim.var)) {
                     reducing_dims.push_back(dim);
                 }
             }