LongRunningNHOperation.cs

 public class LongRunningNHOperation : IDisposable
    {
        SessionScope session;

        int newsessioncount = 250;

        Stopwatch stopwatch = Stopwatch.StartNew();

        private LongRunningNHOperation() { }

        public static LongRunningNHOperation Start(int newsession = 250) {
            return new LongRunningNHOperation() {
                newsessioncount = newsession,
                session = new SessionScope()
            };
        }

        public int OperationCount { get; protected set; }

        public void Iterate() {
            if (++OperationCount % newsessioncount == 0) {
                session.Flush();
                session.Dispose();
                session = new SessionScope();
            }
        }

        public void Dispose() {
            if (session != null) {
                session.Flush();
                session.Dispose();
            }
        }

        public double OperationsSecond {
            get {
                return ((double)OperationCount / stopwatch.ElapsedMilliseconds) * 1000;
            }
        }
    }