diff --git a/crates/accelerate/src/results/marginalization.rs b/crates/accelerate/src/results/marginalization.rs
index 08e1b42e287e..f71511f0e1b6 100644
--- a/crates/accelerate/src/results/marginalization.rs
+++ b/crates/accelerate/src/results/marginalization.rs
@@ -152,24 +152,19 @@ pub fn marginal_memory(
             .collect()
     };
     if return_int {
-        // Replace with:
-        //
-        // .iter()
-        // .map(|x| BigUint::parse_bytes(x.as_bytes(), 2).unwrap())
-        // .collect::<Vec<BigUint>>()
-        // .to_object(py))
-        //
-        // (also this can be done in parallel, see
-        // https://github.com/Qiskit/qiskit-terra/pull/10120 for more
-        // details)
-        //
-        // After PyO3/pyo3#3198 is included in a pyo3 release.
-        let int_pyobject = py.import("builtins")?.getattr("int")?;
-        Ok(out_mem
-            .iter()
-            .map(|x| int_pyobject.call1((x, 2u8)).unwrap())
-            .collect::<Vec<_>>()
-            .to_object(py))
+        if out_mem.len() < parallel_threshold || !run_in_parallel {
+            Ok(out_mem
+                .iter()
+                .map(|x| BigUint::parse_bytes(x.as_bytes(), 2).unwrap())
+                .collect::<Vec<BigUint>>()
+                .to_object(py))
+        } else {
+            Ok(out_mem
+                .par_iter()
+                .map(|x| BigUint::parse_bytes(x.as_bytes(), 2).unwrap())
+                .collect::<Vec<BigUint>>()
+                .to_object(py))
+        }
     } else {
         Ok(out_mem.to_object(py))
     }