Web api, out of memory

    public class FileHelper {
        public static string GetHash(FileInfo file) {
            using (var md5 = MD5.Create()) {
                using (var stream = File.OpenRead(file.FullName)) {
                    return BitConverter.ToString(md5.ComputeHash(stream)).Replace("-", string.Empty);
                }
            }
        }
 
        public static List<FileInfo> GetFiles(string path) {
            DirectoryInfo dir = new DirectoryInfo(path);
            List<FileInfo> result = new List<FileInfo>(dir.GetFiles());
            foreach (var subDir in dir.GetDirectories()) {
                result.AddRange(GetFiles(subDir.FullName));
            }
 
            return result;
        }
    }

    public class FilesController : ApiController
    {
        public ICollection<WidgetFile> Get() {
            var sPath = System.Web.Hosting.HostingEnvironment.MapPath("/Files/");
            return FileHelper.GetFiles(sPath).Where(fi => fi.Name != "launcher.exe" && fi.Name != "launcher_dbg.exe").Select(f => new WidgetFile() {
                Hash = FileHelper.GetHash(f),
                RelativePath = f.FullName.Replace(sPath, string.Empty)
            }).ToArray();
        }
    }

using (var stream = File.OpenRead(file.FullName)) {
     return BitConverter.ToString(md5.ComputeHash(stream)).Replace("-", string.Empty);
}