trying to figure out why foreach is slow

whileLoop.scala

import java.util.Date

object PerfOfWhile extends App {
  def whileLoop(size: Int): Int = {
    var c = 0
    while(c < size){
      c += 1
    }
    c
  }

  def foreachLoop(size: Int): Int = {
    var c = 0
    (1 to size).foreach(_ => c += 1)
    c
  }

  val size = 10000000
  var start = new Date().getTime
  println(s"while loop rs: ${whileLoop(size)}")
  var end = new Date().getTime
  println(s"time used: ${end - start}")

  start = new Date().getTime
  println(s"foreach loop rs: ${foreachLoop(size)}")
  end = new Date().getTime
  println(s"time used: ${end - start}")
}