Program.cs

private static async Task CopySlowly()
{
    Stopwatch sw = new Stopwatch();
    sw.Start();
    var request = new ScanRequest
    {
        TableName = sourceTableName
    };

    var result = await client.ScanAsync(request, default);
    foreach (var item in result.Items)
    {
        var putItemRequest = new PutItemRequest
        {
            TableName = destinationTableNameSlow,
            Item = item
        };

        await client.PutItemAsync(putItemRequest, default);
    }
    sw.Stop();
    Console.Write($"Copy slow - {sw.ElapsedMilliseconds} milliseconds elapsed");
    Console.ReadLine();
}