diff --git a/src/Controls/src/Xaml/XamlLoader.cs b/src/Controls/src/Xaml/XamlLoader.cs
index 82b07624cff9..c4ceb2dcc344 100644
--- a/src/Controls/src/Xaml/XamlLoader.cs
+++ b/src/Controls/src/Xaml/XamlLoader.cs
@@ -61,15 +61,21 @@ public static void Load(object view, string xaml, Assembly rootAssembly, bool us
 		{
 			rootAssembly ??= view.GetType().Assembly;
 
-			var allowImplicitXmlns = rootAssembly.CustomAttributes.Any(a =>
-				   a.AttributeType.FullName == "Microsoft.Maui.Controls.Xaml.Internals.AllowImplicitXmlnsDeclarationAttribute"
-				&& (a.ConstructorArguments.Count == 0 || a.ConstructorArguments[0].Value is bool b && b));
+			if (XamlParser.s_xmlnsPrefixes == null)
+				XamlParser.GatherXmlnsDefinitionAndXmlnsPrefixAttributes(rootAssembly);
+			if (!XamlParser.s_allowImplicitXmlns.TryGetValue(rootAssembly, out var allowImplicitXmlns))
+			{
+				allowImplicitXmlns = rootAssembly.CustomAttributes.Any(a =>
+				   		a.AttributeType.FullName == "Microsoft.Maui.Controls.Xaml.Internals.AllowImplicitXmlnsDeclarationAttribute"
+					&& (a.ConstructorArguments.Count == 0 || a.ConstructorArguments[0].Value is bool b && b));
+				XamlParser.s_allowImplicitXmlns.Add(rootAssembly, allowImplicitXmlns);
+			}
 
 			var nsmgr = new XmlNamespaceManager(new NameTable());
 			if (allowImplicitXmlns)
 			{
 				nsmgr.AddNamespace("", XamlParser.DefaultImplicitUri);
-				foreach (var xmlnsPrefix in XamlParser.GetXmlnsPrefixAttributes())
+				foreach (var xmlnsPrefix in XamlParser.s_xmlnsPrefixes)
 					nsmgr.AddNamespace(xmlnsPrefix.Prefix, xmlnsPrefix.XmlNamespace);
 			}
 			using (var textReader = new StringReader(xaml))
diff --git a/src/Controls/src/Xaml/XamlParser.cs b/src/Controls/src/Xaml/XamlParser.cs
index 0934e9f488d2..71b42d1b4dd6 100644
--- a/src/Controls/src/Xaml/XamlParser.cs
+++ b/src/Controls/src/Xaml/XamlParser.cs
@@ -332,7 +332,8 @@ static IValueNode GetValueNode(object value, XmlReader reader)
 		}
 
 		static IList<XmlnsDefinitionAttribute> s_xmlnsDefinitions;
-
+		internal static IList<XmlnsPrefixAttribute> s_xmlnsPrefixes;
+		internal static Dictionary<Assembly, bool> s_allowImplicitXmlns = new();
 		static bool ValidateProtectedXmlns(string xmlNamespace, string assemblyName)
 		{
 			//maui, and x: xmlns are protected
@@ -348,11 +349,12 @@ static bool ValidateProtectedXmlns(string xmlNamespace, string assemblyName)
 			return false;
 		}
 
-		static void GatherXmlnsDefinitionAttributes(Assembly currentAssembly)
+
+		internal static void GatherXmlnsDefinitionAndXmlnsPrefixAttributes(Assembly currentAssembly)
 		{
 			Assembly[] assemblies = AppDomain.CurrentDomain.GetAssemblies();
 			s_xmlnsDefinitions = [];
-
+			s_xmlnsPrefixes = [];
 			foreach (var assembly in assemblies)
 			{
 				try
@@ -373,6 +375,11 @@ static void GatherXmlnsDefinitionAttributes(Assembly currentAssembly)
 						}
 						s_xmlnsDefinitions.Add(attribute);
 					}
+
+					foreach (XmlnsPrefixAttribute attribute in assembly.GetCustomAttributes(typeof(XmlnsPrefixAttribute), false))
+					{
+						s_xmlnsPrefixes.Add(attribute);
+					}
 				}
 				catch (Exception ex)
 				{
@@ -383,14 +390,6 @@ static void GatherXmlnsDefinitionAttributes(Assembly currentAssembly)
 			}
 		}
 
-		public static IList<XmlnsPrefixAttribute> GetXmlnsPrefixAttributes()
-		{
-			return [.. AppDomain.CurrentDomain.GetAssemblies()
-				.SelectMany(assembly => assembly.GetCustomAttributes(typeof(XmlnsPrefixAttribute), false)
-					.OfType<XmlnsPrefixAttribute>()).Distinct()];
-		}
-
-
 		[RequiresUnreferencedCode(TrimmerConstants.XamlRuntimeParsingNotSupportedWarning)]
 #if !NETSTANDARD
 		[RequiresDynamicCode(TrimmerConstants.XamlRuntimeParsingNotSupportedWarning)]
@@ -402,7 +401,7 @@ public static Type GetElementType(XmlType xmlType, IXmlLineInfo xmlInfo, Assembl
 
 		retry:
 			if (s_xmlnsDefinitions == null)
-				GatherXmlnsDefinitionAttributes(currentAssembly);
+				GatherXmlnsDefinitionAndXmlnsPrefixAttributes(currentAssembly);
 
 			IEnumerable<Type> types = xmlType.GetTypeReferences(
 				s_xmlnsDefinitions,