diff --git a/Assets/UniGLTF/Runtime/Extensions/UnityExtensions.cs b/Assets/UniGLTF/Runtime/Extensions/UnityExtensions.cs
index d92808d9b..4da051b41 100644
--- a/Assets/UniGLTF/Runtime/Extensions/UnityExtensions.cs
+++ b/Assets/UniGLTF/Runtime/Extensions/UnityExtensions.cs
@@ -30,12 +30,31 @@ namespace UniGLTF
 
         public BlendShape(string name)
         {
-            Name = name;
+            Positions = new List<Vector3>();
+            Normals = new List<Vector3>();
+            Tangents = new List<Vector3>();
         }
 
-        public List<Vector3> Positions = new List<Vector3>();
-        public List<Vector3> Normals = new List<Vector3>();
-        public List<Vector3> Tangents = new List<Vector3>();
+        public BlendShape(string name, int vertexCount, bool hasPositions, bool hasNormals, bool hasTangents)
+        {
+            Name = name;
+            if (hasPositions)
+            {
+                Positions = new List<Vector3>(vertexCount);
+            }
+            if (hasNormals)
+            {
+                Normals = new List<Vector3>(vertexCount);
+            }
+            if (hasTangents)
+            {
+                Tangents = new List<Vector3>(vertexCount);
+            }
+        }
+
+        public List<Vector3> Positions { get; private set; }
+        public List<Vector3> Normals { get; private set; }
+        public List<Vector3> Tangents { get; private set; }
     }
 
     public static class UnityExtensions
diff --git a/Assets/UniGLTF/Runtime/UniGLTF/IO/MeshIO/MeshContext.cs b/Assets/UniGLTF/Runtime/UniGLTF/IO/MeshIO/MeshContext.cs
index af6fef0a8..3b5f9c050 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/IO/MeshIO/MeshContext.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/IO/MeshIO/MeshContext.cs
@@ -414,35 +414,38 @@ namespace UniGLTF
                 {
                     for (int i = 0; i < primitives.targets.Count; ++i)
                     {
-                        var blendShape = new BlendShape(i.ToString());
+                        var primTarget = primitives.targets[i];
+                        var blendShape = new BlendShape(i.ToString(), positions.Length, primTarget.POSITION != -1, primTarget.NORMAL != -1, primTarget.TANGENT != -1);
                         _blendShapes.Add(blendShape);
 
-                        var primTarget = primitives.targets[i];
                         if (primTarget.POSITION != -1)
                         {
-                            blendShape.Positions = data.GetArrayFromAccessor<Vector3>(primTarget.POSITION).ToList();
+                            var morphPositions = data.GetArrayFromAccessor<Vector3>(primTarget.POSITION);
+                            blendShape.Positions.Capacity = morphPositions.Length;
                             for (var j = 0; j < blendShape.Positions.Count; ++j)
                             {
-                                blendShape.Positions[j] = inverter.InvertVector3(blendShape.Positions[j]);
+                                blendShape.Positions.Add(inverter.InvertVector3(morphPositions[j]));
                             }
                         }
 
                         if (primTarget.NORMAL != -1)
                         {
-                            blendShape.Normals = data.GetArrayFromAccessor<Vector3>(primTarget.NORMAL).ToList();
+                            var morphNormals = data.GetArrayFromAccessor<Vector3>(primTarget.NORMAL);
+                            blendShape.Normals.Capacity = morphNormals.Length;
                             for (var j = 0; j < blendShape.Positions.Count; ++j)
                             {
-                                blendShape.Normals[j] = inverter.InvertVector3(blendShape.Normals[j]);
+                                blendShape.Normals.Add(inverter.InvertVector3(morphNormals[j]));
                             }
 
                         }
 
                         if (primTarget.TANGENT != -1)
                         {
-                            blendShape.Tangents = data.GetArrayFromAccessor<Vector3>(primTarget.TANGENT).ToList();
+                            var morphTangents = data.GetArrayFromAccessor<Vector3>(primTarget.TANGENT);
+                            blendShape.Tangents.Capacity = morphTangents.Length;
                             for (var j = 0; j < blendShape.Tangents.Count; ++j)
                             {
-                                blendShape.Tangents[j] = inverter.InvertVector3(blendShape.Tangents[j]);
+                                blendShape.Tangents.Add(inverter.InvertVector3(morphTangents[j]));
                             }
                         }
                     }