sharepoint server – Adding a list item in C # takes 5 minutes after the initial update () call

I have a timer job that queries an external list, and then copies the items into a normal SharePoint list. I store the ID of the external list item on the SP list item so that I can update instead of adding, if necessary.

To completely add a new item programmatically, you must call list.Items.Add () to get a new SPListItem object, set the field values ​​on it, and then call item.Update (). The only field I defined when I first added is the field that stores the ID of the external element. There are no mandatory fields. There is no workflow on the SP list. I test this on my development environment and the list of service providers to which new items are added is initially empty.

However, after calling item.Update (), the execution of the code takes about 5 minutes 30 seconds. I log in and I set up a very explicit logging, that's how I see things. Here is the method that allows to add (I've turned the logging code into comments, but that's where the log entries are made):

private SPListItem AddNewItem (SPListItem externalCTItem, SPList list)
// Log: input method

SPListItem newItem = null;
string externalItemID = externalCTItem["ID"].ToString ();
// Log: Call of list.items.add ()
newItem = list.Items.Add ();

// Log: parameter field of the new element
new article["ExternalDB_ID"] = int.Parse (externalItemID);

// Log: Call of newItem.Update ()
newItem.Update ();

// Log: New item created <- it is saved approximately 5m 30s after the last log entry.
catch (Exception ex)
// Log: exception & stacktrace

// Log: existing method
return newItem;

I then go to another method where I define a bunch of other fields, and call item.Update () again after that, and that everything is working fine, the big delay occurs only after the initial update that validates the newly added element.

Why would it take five minutes to add a new item to a list?

Oh, I also want to add that if I go to the SP list, I can see the new element added with the only defined field. Which means that the initial update actually worked, and quickly, that's what happens at the end of item.Update () take forever.