The optimization process and recommendations:

1. Avoid LIKE Searches With Leading Wildcard (query line: 16): The database will not use an index when using like searches with a leading wildcard (e.g. '%%'). Although it's not always a satisfactory solution, please consider using prefix-match LIKE patterns (e.g. 'TERM%').
2. Create Optimal Indexes (modified query below): The recommended indexes are an integral part of this optimization effort and should be created before testing the execution duration of the optimized query.
3. Prefer Inner Join Over Left Join (modified query below): We identified that one or more left joined entities (e.g. `Own`) are used in the 'where' clause, in a way that allows to replace it with an optimized inner join. Inner joins can be fully optimized by the database, while Left joins apply limitations on the database's optimizer.
4. Prefer Inner Join Over Left Join (modified query below): We identified that one or more left joined entities (e.g. `Type`) are used in the 'where' clause, in a way that allows to replace it with an optimized inner join. Inner joins can be fully optimized by the database, while Left joins apply limitations on the database's optimizer.
5. Sort and Limit Before Joining (modified query below): In cases where the joins aren't filtering any rows, it's possible to sort and limit the amount of rows using a subquery in the FROM clause, before applying the joins to all other tables.

Optimal indexes for this query:

ALTER TABLE `Items` ADD INDEX `items_idx_type` (`Type`);
ALTER TABLE `Own` ADD INDEX `own_idx_username_ind` (`Username`,`IND`);
ALTER TABLE `Type` ADD INDEX `type_idx_typename` (`TypeName`);

The optimized query:

SELECT
        i_ind,
        IName AS TName,
        IName AS IName 
    FROM
        (SELECT
            I.IND AS i_ind,
            I.Name AS IName,
            I.Name AS TName 
        FROM
            Items I 
        INNER JOIN
            Type T 
                ON I.Type = T.IND 
        WHERE
            I.Name LIKE '%%' 
            AND T.TypeName = 'New' 
        ORDER BY
            T.Name,
            I.Name LIMIT 100) I 
    INNER JOIN
        Own O 
            ON I.i_ind = O.ItemsIND 
            AND O.Username = 'removed this for other purposes' 
    WHERE
        1 = 1 
        AND (
            O.IND IS NOT NULL
        ) 
        AND (
            1 = 1
        ) LIMIT 100