diff --git a/dev/MethodBinder.Tests/MethodBinderTests.cs b/dev/MethodBinder.Tests/MethodBinderTests.cs
index 44b71b6be..381d17a27 100644
--- a/dev/MethodBinder.Tests/MethodBinderTests.cs
+++ b/dev/MethodBinder.Tests/MethodBinderTests.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Runtime.InteropServices;
 
 using Python.Runtime;
 
@@ -97,6 +96,16 @@ public void TestFooParam_2()
             t = I.Foo(IntPtr.Zero, 0);
             r = MethodInvoke.Invoke<Guid>(I, M, args, NoKwargs);
             Assert.That(t, Is.EqualTo(r));
+
+            // Foo([Optional, DefaultParameterValue(12)] nint _1, uint _2)
+            args = new object[] { 0 };
+            var kwargs = new KeywordArgs
+            {
+                ["_1"] = IntPtr.Zero,
+            };
+            t = I.Foo(_1: IntPtr.Zero, 0);
+            r = MethodInvoke.Invoke<Guid>(I, M, args, kwargs);
+            Assert.That(t, Is.EqualTo(r));
         }
     }
 }
diff --git a/src/runtime/MethodBinder.Invoke.cs b/src/runtime/MethodBinder.Invoke.cs
index cb6bc23b1..6acdfe838 100644
--- a/src/runtime/MethodBinder.Invoke.cs
+++ b/src/runtime/MethodBinder.Invoke.cs
@@ -6,6 +6,7 @@
 namespace Python.Runtime
 {
     using KeywordArgs = Dictionary<string, object?>;
+    using TypeDistMap = Dictionary<int, uint>;
 
 #if UNIT_TEST
     public static class MethodInvoke
@@ -23,6 +24,8 @@ internal partial class MethodBinder
         static readonly Type UNINT = typeof(nuint);
         static readonly Type NINT = typeof(nint);
 
+        static readonly TypeDistMap s_distMap = new();
+
         private sealed class MatchArgSlot
         {
             readonly ParameterInfo _paramInfo;
@@ -225,13 +228,17 @@ static uint GetDistance(Type from, Type to)
             {
                 uint distance;
 
+                int key = from.GetHashCode() + to.GetHashCode();
+                if (s_distMap.TryGetValue(key, out uint dist))
+                {
+                    return dist;
+                }
+
                 if (from == to)
                 {
                     distance = 0;
                 }
                 else if (from.IsAssignableFrom(to))
-                            //|| CanCast(from, to)
-                            //|| CanCast(to, from))
                 {
                     distance = 1;
                 }
@@ -244,6 +251,8 @@ static uint GetDistance(Type from, Type to)
                         );
                 }
 
+                s_distMap[key] = distance;
+
                 return distance;
             }