sample(x, length) or x[runif(length, 1:(length(x)+1))] : what is the most rapid?

microbenchmark(
  sample(x = x, size=1000L, replace = TRUE)
, sample(x = x, size=1000, replace = TRUE)
, x[floor(runif(1000L, 1L, length(x)+1L))]
, x[floor(runif(1000, 1, length(x)+1))]
, x[runif(1000L, 1L, length(x)+1L)]
, x[runif(1000, 1, length(x)+1)]
, times = 10000L
)

Unit: microseconds
                                        expr    min      lq     mean  median      uq
 sample(x = x, size = 1000L, replace = TRUE) 42.202 46.0750 51.70049 50.4445 53.1295
  sample(x = x, size = 1000, replace = TRUE) 41.433 46.0935 51.52335 50.5570 53.0650
  x[floor(runif(1000L, 1L, length(x) + 1L))] 40.027 42.2450 49.22916 49.5545 52.0355
     x[floor(runif(1000, 1, length(x) + 1))] 40.112 42.1865 59.03723 49.5050 51.9370
         x[runif(1000L, 1L, length(x) + 1L)] 37.124 39.2570 46.15197 46.4555 48.9570
            x[runif(1000, 1, length(x) + 1)] 37.093 39.1935 54.89901 46.3630 48.7875

In conclusion, the most rapid is 
x[runif(1000, 1, length(x) + 1)]

But the difference is not very important.

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