R: optimal way of computing the "product" of two vectors -

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Assuming I have a vector 

  r  rnorm (4)   
 and a matrix  w  dimension 20000 * 200: 
 
  w < - I want to calculate a new matrix  M  dimension 5000 * 200; matrix (rnorm (20000 * 200), 20000,200)  
 
 Code> m11 & lt; - r% *% W [1: 4,1] ,  m21 & lt; - r% *% W [5: 8,1] ,  m12 & lt; - r% *% w [1: 4,2]  etc. (i.e. calculating four to four-fourth productive sections and product). 
 
 What is the optimal (speed, memory) way of doing this? 
 
 Thanks in advance.

This seems to run fastest for me: 

  array (R% *% array (w, c (4, 20000 * 200/4)), c (5000, 200))

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