How do I speed up below Sharepoint CSOM code? - sharepoint

Question

I have below CSOM code to delete all list items from the list. But it is very slow. How can I make it faster.
public void DeleteListData()
{
string root = "mysite.com/";
using (ClientContext clientContext = new ClientContext(root))
{
Web web = clientContext.Web;
List list = web.Lists.GetByTitle("Search");
var query = new CamlQuery() { ViewXml = "<View><Query><Where><IsNotNull><FieldRef Name='First_x0020_Name' /></IsNotNull></Where></Query></View>" };
var items = list.GetItems(query);
clientContext.Load(items);
clientContext.ExecuteQuery();
var count = items.Count;
if (count > 0)
{
for (int i = 0; i < count; i++)
{
items[i].DeleteObject();
items[i].Update();
}
}
clientContext.ExecuteQuery();
}
}

Answer 1

Almost fine according to my knowledge, just trying to add batch logic to limit deleting items count each query.
I think below code is good sample.
andyhuey/deleteAllFromList.cs
private void deleteAllFromList(ClientContext cc, List myList)
{
int queryLimit = 4000;
int batchLimit = 100;
bool moreItems = true;
string viewXml = string.Format(#"
<View>
<Query><Where></Where></Query>
<ViewFields>
<FieldRef Name='ID' />
</ViewFields>
<RowLimit>{0}</RowLimit>
</View>", queryLimit);
var camlQuery = new CamlQuery();
camlQuery.ViewXml = viewXml;
while (moreItems)
{
ListItemCollection listItems = myList.GetItems(camlQuery); // CamlQuery.CreateAllItemsQuery());
cc.Load(listItems,
eachItem => eachItem.Include(
item => item,
item => item["ID"]));
cc.ExecuteQuery();
var totalListItems = listItems.Count;
if (totalListItems > 0)
{
Console.WriteLine("Deleting {0} items from {1}...", totalListItems, myList.Title);
for (var i = totalListItems - 1; i > -1; i--)
{
listItems[i].DeleteObject();
if (i % batchLimit == 0)
cc.ExecuteQuery();
}
cc.ExecuteQuery();
}
else
{
moreItems = false;
}
}
Console.WriteLine("Deletion complete.");
}