MainForm.cs

using System;
using System.Collections.Generic;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ImageLoad
{
    public partial class MainForm : Form
    {
        Bitmap[] bitmaps;

        public MainForm()
        {
            InitializeComponent();
        }

        private void MainForm_Load(object sender, EventArgs e)
        {
            IEnumerable<FileInfo> resources = new DirectoryInfo("Resources").EnumerateFiles("*.png", SearchOption.AllDirectories);
            listView.Items.AddRange(resources.Select(selector => new ListViewItem(selector.Name)).ToArray());
            bitmaps = new Bitmap[resources.Count()];
            Parallel.ForEach(resources.Select((file, index) => new { file, index }), item => bitmaps[item.index] = new Bitmap(item.file.OpenRead())/*.Clone(new Rectangle(0, 0, 16, 16), PixelFormat.Canonical)*/);
        }

        private void listView_DrawItem(object sender, DrawListViewItemEventArgs e)
        {
            e.Graphics.DrawImageUnscaledAndClipped(bitmaps[e.ItemIndex], e.Bounds);
            if (e.State.HasFlag(ListViewItemStates.Selected)) Text = e.Item.Text;
            else if (e.State.HasFlag(ListViewItemStates.Focused)) Text = "";
        }
    }
}