Two solutions for progress bar... not equivalent

To make a progress bar, you have two main solutions:
In library utils: txtProgressBar()
In library progress: progress_bar$new()

The second one makes a progress bar with automatic "estimated time to arrival". This is very useful. However, it does that functionality at a cost.
Let do 3 examples: without progress bar, with a txtProgressBar() and with a progress_bar$new() (see below for the codes).

The code is ran in Rstudio, R GUI and in terminal under MacOSX:

Rstudio:
> A[3]/R[3]
 elapsed 
8.235853 
> B[3]/R[3]
 elapsed 
1.835827 

R GUI:
> A[3]/R[3]
 elapsed 
7.895495 
> B[3]/R[3]
 elapsed 
1.181143 

R in terminal:

> A[3]/R[3]

 elapsed 

10.74719 

> B[3]/R[3]

 elapsed 

2.079948 

In conclusion, the progress_bar$new() is between 5 to 8 time slower than the txtProgressBar(). It is nicer but it has a cost !

R <- system.time({
  Total <- 50000
  for (annee in 1:Total) {
    Sys.sleep(0.0001)
  }
})

library("progress")
A <- system.time({
       Total <- 50000
       pb <- progress_bar$new(
             format = "  completion [:bar] :percent eta: :eta",
             total = Total, clear = FALSE)
       for (annee in 1:Total) {
             pb$tick()
             Sys.sleep(0.0001)
       }
       cat("\n")
 })

library("utils")

B <- system.time({
  Total <- 50000
  pb <- txtProgressBar(min=0, max=Total, style=3)
  for (annee in 1:Total) {
    setTxtProgressBar(pb, annee)
    Sys.sleep(0.0001)
  }
  cat("\n")
})

A[3]/R[3]
B[3]/R[3]