diff --git a/src/Foundation/NSObject2.cs b/src/Foundation/NSObject2.cs
index 02297f793693..299b32ec8468 100644
--- a/src/Foundation/NSObject2.cs
+++ b/src/Foundation/NSObject2.cs
@@ -475,6 +475,34 @@ public virtual bool ConformsToProtocol (NativeHandle protocol)
 			if (!Runtime.DynamicRegistrationSupported)
 				return false;
 
+			// the linker/trimmer will remove the following code if the dynamic registrar is removed from the app
+			var classHandle = ClassHandle;
+			lock (Runtime.protocol_cache) {
+#if NET
+				ref var map = ref CollectionsMarshal.GetValueRefOrAddDefault (Runtime.protocol_cache, classHandle, out var exists);
+				if (!exists)
+					map = new ();
+				ref var result = ref CollectionsMarshal.GetValueRefOrAddDefault (map, protocol, out exists);
+				if (!exists)
+					result = DynamicConformsToProtocol (protocol);
+#else
+				bool new_map = false;
+				if (!Runtime.protocol_cache.TryGetValue (classHandle, out var map)) {
+					map = new ();
+					new_map = true;
+					Runtime.protocol_cache.Add (classHandle, map);
+				}
+				if (new_map || !map.TryGetValue (protocol, out var result)) {
+					result = DynamicConformsToProtocol (protocol);
+					map.Add (protocol, result);
+				}
+#endif
+				return result;
+			}
+		}
+
+		bool DynamicConformsToProtocol (NativeHandle protocol)
+		{
 			object [] adoptedProtocols = GetType ().GetCustomAttributes (typeof (AdoptsAttribute), true);
 			foreach (AdoptsAttribute adopts in adoptedProtocols){
 				if (adopts.ProtocolHandle == protocol)
diff --git a/src/ObjCRuntime/Runtime.cs b/src/ObjCRuntime/Runtime.cs
index 2e65eab6e1bd..bfcebcaac387 100644
--- a/src/ObjCRuntime/Runtime.cs
+++ b/src/ObjCRuntime/Runtime.cs
@@ -35,6 +35,7 @@ public partial class Runtime {
 		static Dictionary<IntPtrTypeValueTuple,Delegate> block_to_delegate_cache;
 		static Dictionary<Type, ConstructorInfo> intptr_ctor_cache;
 		static Dictionary<Type, ConstructorInfo> intptr_bool_ctor_cache;
+		internal static Dictionary<IntPtr, Dictionary<IntPtr, bool>> protocol_cache;
 
 		static List <object> delegates;
 		static List <Assembly> assemblies;
@@ -280,8 +281,10 @@ unsafe static void Initialize (InitializationOptions* options)
 
 			NSObjectClass = NSObject.Initialize ();
 
-			if (DynamicRegistrationSupported)
+			if (DynamicRegistrationSupported) {
 				Registrar = new DynamicRegistrar ();
+				protocol_cache = new Dictionary<IntPtr, Dictionary<IntPtr, bool>> (IntPtrEqualityComparer);
+			}
 			RegisterDelegates (options);
 			Class.Initialize (options);
 #if !NET