Fastest way to count occurrences of each unique element

Question

What is the fastest way to compute the number of occurrences for each unique element in a vector in R?

So far, I\'ve tried the following five functions:

Answer 1

There's almost nothing that will beat tabulate() provided you can meet the initial conditions.

x <- sample(1:100, size=1e7, TRUE)
system.time(tabulate(x))
#  user  system elapsed 
# 0.071   0.000   0.072 

@dickoa adds a few more notes in the comments as to how to get the appropriate output, but tabulate as a workhorse function is the way to go.