Heavy-NP shift

displacement of a so-called heavy NP (an NP which is prosodically 'heavy', i.e. contains a large amount of phonological material) to the right edge of the sentence:

(i) a They sent [that book that only got good reviews in the New York Times] to Mary b They sent t to Mary [that book that only got good reviews in the New York Times]

Heavy-NP shift presumably is a so-called stylistic rule, i.e. a rule which does not belong to core grammar. It may be related to scrambling since it is not a case of A-movement.

Link
Utrecht Lexicon of Linguistics