Fast psuedo UUID generation in Scala

FastUUID.scala

import java.util.concurrent.ThreadLocalRandom
import scala.annotation.tailrec

object FastUUID extends App {

  val hex = "0123456789abcdef".toCharArray

  def fastUUID(): String = {
    val msbees = ThreadLocalRandom.current.nextLong()
    val lsbees = ThreadLocalRandom.current.nextLong()
    val sb = new StringBuilder(36)

    @tailrec
    def appendHex(l: Long, d: Int, acc: StringBuilder): Unit = {
      if (d != 0) {
        appendHex(l >> 4, d - 1, acc.append(hex((l & 0xf).toInt)))
      }
    }

    appendHex(msbees, 8, sb)
    sb.append("-")
    appendHex(msbees >> 32, 4, sb)
    sb.append("-")
    appendHex(msbees >> 48, 4, sb)
    sb.append("-")
    appendHex(lsbees, 4, sb)
    sb.append("-")
    appendHex(lsbees >> 16, 12, sb)
    sb.toString
  }

  def timeIt(method: => String): Long = {
    val before = System.nanoTime()
    for (_ <- 1 to 1000000) method
    System.nanoTime() - before
  }

  timeIt(java.util.UUID.randomUUID().toString)
  print("javaUUID timed : ")
  val j = timeIt(java.util.UUID.randomUUID().toString)
  println(j)

  timeIt(fastUUID)
  print("fastUUID timed : ")
  val ft = timeIt(fastUUID)
  println(ft)

  println("javaUUID Time / fastUUID Time " + j.toDouble / ft)
}