public class MeshLister : EditorWindow
{
    [MenuItem("Tools/Mesh Lister")]
    static void Open() { GetWindow<MeshLister>(); }

    struct Info
    {
        public Mesh mesh;
        public int subMeshes;
        public int triCount;
        public int total;
        public int occurences;
        public string file;
    };

    Info[] infos;
    Vector2 scrollPosition;
    int totalTriCount;

    private void OnGUI()
    {
        if (GUILayout.Button("Refresh"))
        {
            Dictionary<Mesh, int> meshSet = new Dictionary<Mesh, int>();

            MeshFilter[] meshFilters = FindObjectsOfType<MeshFilter>();
            foreach (MeshFilter mf in meshFilters)
                if (meshSet.ContainsKey(mf.sharedMesh)) meshSet[mf.sharedMesh]++; else meshSet.Add(mf.sharedMesh, 1);

            SkinnedMeshRenderer[] skinnedMeshs = FindObjectsOfType<SkinnedMeshRenderer>();
            foreach (SkinnedMeshRenderer skinned in skinnedMeshs)
                if (meshSet.ContainsKey(skinned.sharedMesh)) meshSet[skinned.sharedMesh]++; else meshSet.Add(skinned.sharedMesh, 1);

            ParticleSystemRenderer[] particles = FindObjectsOfType<ParticleSystemRenderer>();
            foreach (ParticleSystemRenderer fx in particles)
                if (fx.renderMode == ParticleSystemRenderMode.Mesh && fx.mesh != null)
                    if (meshSet.ContainsKey(fx.mesh)) meshSet[fx.mesh]++; else meshSet.Add(fx.mesh, 1);

            Mesh[] meshes = new Mesh[meshSet.Keys.Count];
            meshSet.Keys.CopyTo(meshes, 0);

            totalTriCount = 0;
            infos = new Info[meshes.Length];
            for (int i = 0; i < meshes.Length; i++)
            {
                infos[i].mesh = meshes[i];
                infos[i].occurences = meshSet[meshes[i]];
                infos[i].file = string.Empty;
                if (meshes[i] == null)
                    continue;
                infos[i].subMeshes = meshes[i].subMeshCount;

                int count = 0;
                for (int j = 0; j < infos[i].subMeshes; j++)
                    count += meshes[i].GetTriangles(j).Length / 3;
                infos[i].triCount = count;

                string path = AssetDatabase.GetAssetPath(meshes[i]);
                infos[i].file = System.IO.Path.GetFileName(path);

                infos[i].total = infos[i].triCount * infos[i].occurences;
                totalTriCount += infos[i].total;
            }
        }

        EditorGUILayout.BeginHorizontal();
        GUILayout.Label("Mesh", EditorStyles.boldLabel, GUILayout.Width(200));
        if (GUILayout.Button("File", EditorStyles.boldLabel))
            Array.Sort(infos, (lhs, rhs) => { return lhs.file.CompareTo(rhs.file); });
        if (GUILayout.Button("Occurences", EditorStyles.boldLabel, GUILayout.Width(80)))
            Array.Sort(infos, (lhs, rhs) => { return rhs.occurences - lhs.occurences; });
        if (GUILayout.Button("SubMeshes", EditorStyles.boldLabel, GUILayout.Width(80)))
            Array.Sort(infos, (lhs, rhs) => { return rhs.subMeshes - lhs.subMeshes; });
        if (GUILayout.Button("Triangles", EditorStyles.boldLabel, GUILayout.Width(80)))
            Array.Sort(infos, (lhs, rhs) => { return rhs.triCount - lhs.triCount; });
        if (GUILayout.Button("Total", EditorStyles.boldLabel, GUILayout.Width(80)))
            Array.Sort(infos, (lhs, rhs) => { return rhs.total - lhs.total; });
        EditorGUILayout.EndHorizontal();

        if (infos != null)
        {
            scrollPosition = GUILayout.BeginScrollView(scrollPosition);
            for (int i = 0; i < infos.Length; i++)
            {
                EditorGUILayout.BeginHorizontal();
                EditorGUILayout.ObjectField(infos[i].mesh, typeof(Mesh), false, GUILayout.Width(200));
                GUILayout.Label(infos[i].file);
                GUILayout.Label(infos[i].occurences.ToString(), GUILayout.Width(80));
                GUILayout.Label(infos[i].subMeshes.ToString(), GUILayout.Width(80));
                GUILayout.Label(infos[i].triCount.ToString(), GUILayout.Width(80));
                GUILayout.Label(infos[i].total.ToString(), GUILayout.Width(80));
                EditorGUILayout.EndHorizontal();
            }
            GUILayout.EndScrollView();

            GUILayout.Label(string.Format("Total triangle count: {0}", totalTriCount));
        }
    }
}