SharePoint SPWeb.ProcessBatch & Object model

using System;
using System.Diagnostics;
using System.Text;
using Microsoft.SharePoint;

namespace Demo
{
    class Program
    {
        static void Main(String[] args)
        {
            using (SPSite site = new SPSite("http://sp"))
            {
                Int32 itemsCount                            = 1000;
                SPList list                                 = site.RootWeb.GetList("http://sp/Lists/Clients/");

                Stopwatch sw                                = new Stopwatch();
                Console.WriteLine("Begin adding {0} items", itemsCount);
                sw.Start();

                for (Int32 i = 0; i < itemsCount; i++)
                {
                    SPListItem newItem                      = list.AddItem();
                    newItem["Title"]                        = "New client";
                    newItem["FullName"]                     = "New client full name";
                    newItem["Discount"]                     = i;
                    newItem.Update();
                }
                sw.Stop();
                Console.WriteLine("Items added per {0}", sw.Elapsed);
                sw.Reset();

                SPQuery query                               = new SPQuery{ ViewFields = String.Format("<FieldRef ID='{0}' />", SPBuiltInFieldId.ID) };
                SPListItemCollection items                  = list.GetItems(query);
                Console.WriteLine("Begin updating {0} items", items.Count);

                sw.Start();

                foreach (SPListItem item in items)
                {
                    item["Title"]                           = "New client";
                    item["FullName"]                        = "New client full name";
                    item["Discount"]                        = item.ID;
                    item.Update();
                }

                sw.Stop();
                Console.WriteLine("Items updated per {0}", sw.Elapsed);
                sw.Reset();

                Console.WriteLine("Begin deleting {0} items", items.Count);
                sw.Start();

                while (items.Count > 0)
                    items[0].Delete();

                sw.Stop();
                Console.WriteLine("Items deleted per {0}", sw.Elapsed);
                sw.Reset();


                Console.WriteLine("Begin adding {0} items with batch", itemsCount);
                sw.Start();

                String addItemBatchFormat                   = String.Format(
                                                                    @"<Method ID='Adding item {{0}}'>
                                                                        <SetList Scope='Request'>{0}</SetList>
                                                                        <SetVar Name='Cmd'>Save</SetVar>
                                                                        <SetVar Name='ID'>New</SetVar>
                                                                        <SetVar Name='urn:schemas-microsoft-com:office:office#Title'>{{1}}</SetVar>
                                                                        <SetVar Name='urn:schemas-microsoft-com:office:office#FullName'>{{2}}</SetVar>
                                                                        <SetVar Name='urn:schemas-microsoft-com:office:office#Discount'>{{0}}</SetVar>
                                                                    </Method>", list.ID);

                StringBuilder batchBuilder                  = new StringBuilder("<?xml version=\"1.0\" encoding=\"UTF-8\"?><ows:Batch OnError=\"Continue\">");
                for (Int32 i = 0; i < itemsCount; i++)
                    batchBuilder.AppendFormat(addItemBatchFormat, i, "New client", "New client full name");

                batchBuilder.Append("</ows:Batch>");
                site.RootWeb.ProcessBatchData(batchBuilder.ToString());

                sw.Stop();
                Console.WriteLine("Items added per {0}", sw.Elapsed);
                sw.Reset();

                items                                       = list.GetItems(query);
                Console.WriteLine("Begin updating {0} items with batch", items.Count);
                sw.Start();
                String updateItemBatchFormat                = String.Format(
                                                                    @"<Method ID='Updating item with ID {{0}}'>
                                                                        <SetList Scope='Request'>{0}</SetList>
                                                                        <SetVar Name='Cmd'>Save</SetVar>
                                                                        <SetVar Name='ID'>{{0}}</SetVar>
                                                                        <SetVar Name='urn:schemas-microsoft-com:office:office#Title'>{{1}}</SetVar>
                                                                        <SetVar Name='urn:schemas-microsoft-com:office:office#FullName'>{{2}}</SetVar>
                                                                        <SetVar Name='urn:schemas-microsoft-com:office:office#Discount'>{{0}}</SetVar>
                                                                    </Method>", list.ID);
                batchBuilder                                = new StringBuilder("<?xml version=\"1.0\" encoding=\"UTF-8\"?><ows:Batch OnError=\"Continue\">");
                foreach (SPListItem item in items)
                    batchBuilder.AppendFormat(updateItemBatchFormat, item.ID, "New client", "New client full name");

                batchBuilder.Append("</ows:Batch>");
                site.RootWeb.ProcessBatchData(batchBuilder.ToString());

                sw.Stop();
                Console.WriteLine("Items updated per {0}", sw.Elapsed);
                sw.Reset();


                Console.WriteLine("Begin deleting {0} items with batch", items.Count);
                sw.Start();
                query                                       = new SPQuery{ ViewFields = String.Format("<FieldRef ID='{0}' />", SPBuiltInFieldId.ID) };
                items                                       = list.GetItems(query);
                String deleteItemBatchFormat                = String.Format(
                                                                    @"<Method ID='Updating item with ID {{0}}'>
                                                                        <SetList Scope='Request'>{0}</SetList>
                                                                        <SetVar Name='Cmd'>Delete</SetVar>
                                                                        <SetVar Name='ID'>{{0}}</SetVar>
                                                                    </Method>", list.ID);
                batchBuilder                                = new StringBuilder("<?xml version=\"1.0\" encoding=\"UTF-8\"?><ows:Batch OnError=\"Continue\">");
                foreach (SPListItem item in items)
                    batchBuilder.AppendFormat(deleteItemBatchFormat, item.ID);

                batchBuilder.Append("</ows:Batch>");
                site.RootWeb.ProcessBatchData(batchBuilder.ToString());

                sw.Stop();
                Console.WriteLine("Items deleted per {0}", sw.Elapsed);
            }
            Console.ReadKey();
        }
    }
}