diff --git a/src/Xamarin.Android.Build.Tasks/Utilities/RtxtParser.cs b/src/Xamarin.Android.Build.Tasks/Utilities/RtxtParser.cs
index d2d1f6aa42b..151db3ae919 100644
--- a/src/Xamarin.Android.Build.Tasks/Utilities/RtxtParser.cs
+++ b/src/Xamarin.Android.Build.Tasks/Utilities/RtxtParser.cs
@@ -5,35 +5,35 @@
 using System.Text.RegularExpressions;
 using Microsoft.Android.Build.Tasks;
 using Microsoft.Build.Utilities;
+using System.Runtime.InteropServices;
 
 namespace Xamarin.Android.Tasks
 {
-	public enum RType {
+	public enum RType : byte {
 		Integer,
+		Integer_Styleable,
 		Array,
 	}
 
-	public enum ResourceType {
+	public enum ResourceType : byte {
 		System,
 		Custom,
 	}
 
+	[StructLayout(LayoutKind.Sequential)]
 	public struct R : IComparable<R> {
-		public RType Type;
 		public int Id;
+		public RType Type;
+		public ResourceType ResourceType;
 		public int [] Ids;
 		public string Identifier;
 		public string ResourceTypeName;
-		public ResourceType ResourceType;
-
 		public string Key => $"{ResourceTypeName}:{Identifier}";
 
 		public override string ToString ()
 		{
-			if (Type == RType.Integer) {
-				if (ResourceTypeName == "styleable")
-					return $"int {ResourceTypeName} {Identifier} {Id}";
-				return $"int {ResourceTypeName} {Identifier} 0x{Id.ToString ("x8")}";
+			if (Type != RType.Array) {
+				return $"int {ResourceTypeName} {Identifier} { (Type == RType.Integer ? $"0x{Id.ToString ("x8")}" : "{Id}")}";
 			}
 			return $"int[] {ResourceTypeName} {Identifier} {{ {String.Join (", ", Ids.Select (x => $"0x{x.ToString ("x8")}"))} }}";
 		}
@@ -104,10 +104,13 @@ public IEnumerable<R> Parse (string file, TaskLoggingHelper logger, Dictionary<s
 			return result;
 		}
 
-		void ProcessRtxtFile (string file, IList<R> result)
+		void ProcessRtxtFile (string file, List<R> result)
 		{
+			var lines = File.ReadAllLines (file);
+			result.Capacity = lines.Length;
+
 			int lineNumber = 0;
-			foreach (var line in File.ReadLines (file)) {
+			foreach (var line in lines) {
 				lineNumber++;
 				var items = line.Split (EmptyChar, 4);
 				if (items.Length < 4) {
@@ -119,11 +122,13 @@ void ProcessRtxtFile (string file, IList<R> result)
 					continue;
 				}
 				int value = items [1] != "styleable" ? Convert.ToInt32 (items [3].Trim (), 16) : -1;
+				var type = items [1] != "styleable" ? RType.Integer : RType.Integer_Styleable;
 				string itemName = ResourceIdentifier.GetResourceName(ResourceParser.GetNestedTypeName (items [1]), items [2], map, log);
 				if (knownTypes.Contains (items [1])) {
 					if (items [1] != "styleable") {
 						result.Add (new R () {
 							ResourceTypeName = items [1],
+							Type =type,
 							Identifier = itemName,
 							Id = value,
 						});
@@ -133,6 +138,7 @@ void ProcessRtxtFile (string file, IList<R> result)
 						case "int":
 							result.Add (new R () {
 								ResourceTypeName = items [1],
+								Type = type,
 								Identifier = itemName,
 								Id = Convert.ToInt32 (items [3].Trim (), 10),
 							});