diff --git a/src/rewrite/exploitation.rs b/src/rewrite/exploitation.rs
index eef0708..11bcc14 100644
--- a/src/rewrite/exploitation.rs
+++ b/src/rewrite/exploitation.rs
@@ -42,7 +42,9 @@ use super::normal_form::SpjNormalForm;
 use super::QueryRewriteOptions;
 
 /// A cost function. Used to evaluate the best physical plan among multiple equivalent choices.
-pub type CostFn = Arc<dyn Fn(&dyn ExecutionPlan) -> f64 + Send + Sync>;
+pub type CostFn = Arc<
+    dyn for<'a> Fn(Box<dyn Iterator<Item = &'a dyn ExecutionPlan> + 'a>) -> Vec<f64> + Send + Sync,
+>;
 
 /// A logical optimizer that generates candidate logical plans in the form of [`OneOf`] nodes.
 #[derive(Debug)]
@@ -346,9 +348,10 @@ impl OneOfExec {
                 "can't create OneOfExec with empty children".to_string(),
             ));
         }
-        let best = candidates
+
+        let best = cost(Box::new(candidates.iter().map(|c| c.as_ref())))
             .iter()
-            .position_min_by_key(|candidate| OrderedFloat(cost(candidate.as_ref())))
+            .position_min_by_key(|&cost| OrderedFloat(*cost))
             .unwrap();
 
         Ok(Self {
@@ -441,11 +444,7 @@ impl ExecutionPlan for OneOfExec {
 
 impl DisplayAs for OneOfExec {
     fn fmt_as(&self, t: DisplayFormatType, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        let costs = self
-            .children()
-            .iter()
-            .map(|c| (self.cost)(c.as_ref()))
-            .collect_vec();
+        let costs = (self.cost)(Box::new(self.children().iter().map(|arc| arc.as_ref())));
         match t {
             DisplayFormatType::Default | DisplayFormatType::Verbose => {
                 write!(