Comment by ltjohnson

You gotta do what you gotta do, but your example probably doesn't do what you want in R.

  > system.time(vec1 <- rnorm(1000000))
     user  system elapsed 
    0.200   0.000   0.199 

My computer takes .2 seconds to generate the million random normals and assign them to vec1.

  > vec1 = rnorm(1000000)
  > system.time(vec1)
     user  system elapsed 
        0       0       0 
 

My computer only takes 0 seconds to evaluate the existing vec1 of length one million.