The optimization process and recommendations:

1. 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.

Optimal indexes for this query:

ALTER TABLE `tFoundWords` ADD INDEX `tfoundwords_idx_wordfromkladr` (`WordFromKladr`);
ALTER TABLE `tKladrItems` ADD INDEX `tkladritems_idx_id` (`id`);
ALTER TABLE `tWordKladrItems` ADD INDEX `twordkladritems_idx_wordid` (`wordID`);

The optimized query:

SELECT
        dbo.tKladrItems.KladrItemName,
        dbo.tFoundWords.WordFromAddressString,
        dbo.tFoundWords.WordFromKladr,
        dbo.tFoundWords.WordPosition AS WordPositionAddressString,
        dbo.tWordKladrItems.wordNumber AS WordPositionKladrItem,
        dbo.tFoundWords.StartPosition,
        dbo.tFoundWords.EndPosition,
        dbo.tFoundWords.Metric,
        dbo.tFoundWords.IsConstruction,
        dbo.tKladrItems.WordsCount,
        dbo.tKladrItems.Indeces 
    FROM
        dbo.tWordsFromKladr 
    JOIN
        dbo.tWordKladrItems 
            ON dbo.tWordsFromKladr.ID = dbo.tWordKladrItems.wordID 
    JOIN
        dbo.tFoundWords 
            ON dbo.tFoundWords.WordFromKladr = dbo.tWordsFromKladr.WordFromKladr 
    JOIN
        dbo.tKladrItems 
            ON dbo.tWordKladrItems.kladrItemID = dbo.tKladrItems.id