XNA Texture2D caching
public class ContentCache
{
    private readonly ContentManager _content;
    private readonly Dictionary<string, Texture2D> _textureCache = new Dictionary<string, Texture2D>();

    public ContentCache(ContentManager content)
    {
        _content = content;
    }

    public Texture2D Load(string assetName)
    {
        Texture2D texture = null;
        if (!_textureCache.TryGetValue(assetName, out texture))
        {
            _textureCache[assetName] =
                texture = _content.Load<Texture2D>(assetName);
        }
        return texture;
    }
}

// Preload assets
static readonly string[] preloadAssets =
{
     "Textures\texture1",
};

protected override void LoadContent()
{
    foreach ( string asset in preloadAssets )
    {
        Content.Load<object>(asset);
    }
}