Perhaps I might included simple examples that can be covered easily by ITVF but generally speaking I tried to show out generic T-SQL practices to address any performance issue of TVFs

In addition, I consider largely DB stress powers so using Temp table might be sometimes much powerful if replacing MTVF or ITVF if they are used within joins with other tables but you need to check that along with your T-SQL queries and I recommend heavily for your to rely any DB stress tool like SQLQueryStress

Once again …Thx for your follow and comments

Try this in a test environment:

USE tempdb;
GO
CREATE TABLE #T (ObjectID INT, IndexID INT);

INSERT INTO #T (ObjectID, IndexID)
SELECT OBJECT_ID, index_id
FROM sys.indexes;
GO
DECLARE @T TABLE (
ID INT IDENTITY PRIMARY KEY,
Col1 INT NOT NULL UNIQUE);

SELECT sys.indexes.OBJECT_ID, sys.indexes.index_id
FROM sys.indexes
EXCEPT
SELECT ObjectID, IndexID
FROM #T;
GO
DECLARE @T TABLE (
ID INT IDENTITY PRIMARY KEY,
Col1 INT NOT NULL);

SELECT sys.indexes.OBJECT_ID, sys.indexes.index_id
FROM sys.indexes
EXCEPT
SELECT ObjectID, IndexID
FROM #T;
GO
DROP TABLE #T;

What you’ll see is that the table variable declared with a UNIQUE constraint generates an index, which shows up in sys.indexes. You’ll see the PK clustered index in there too.

Once again thanks for your comments

Once again thanks for your comments