Performance drop under SL5 runtime

private void GotCustomers(EntityQueryOperation<Customer> args) {
    _localOutput.Append(string.Format("[{0}] Retrieved {1} customers\n",
    _nameBasicQuerySyntaxQuery, args.Results.Count()));

    #region New Code
        
    var start = DateTime.UtcNow;

    //This is mostly just a dummy variable so we know that the code doesn't get optimized away
    long dummyCounter = 0;

    //Go through all customers
    foreach (var customer in args.Results)
    {
        //Loop a bunch of times so we have more accurate timings
        for(var i = 1;i<100000;i++ )
            //Access the .City property (which will eventually call DataEntityProperty.GetValue() which seem
            //   to be a lot slower now)
            dummyCounter += customer.City.Length;
    }

    //Print out the elapsed time
    var elapsed = (DateTime.UtcNow - start).TotalSeconds;
    _localOutput.AppendFormat("Silverlight Version {0} took {1} seconds", Environment.Version, elapsed);

    #endregion
        
    Utility.FlushOutputBuffer(_localOutput, _resultsReporter);
}