string_format_micro_bench.scala

def timeLoops (loops: Int)(f: => Any) = {
  val t1 = System.currentTimeMillis
  for(i <- 1 to loops)
    f
  val elapsed = System.currentTimeMillis - t1
  println("executed %d loops in %d ms, or %.2f loops/sec".format(
    loops, elapsed, loops/(elapsed/1000.0)))
}

val loops = 1000000
val slices = Array("this has a string", "and another string")
val replacements = Array("string1", "string2")
val both = slices.zip(replacements)
val fmtString = slices.mkString(" (%s) ")

println("running %d loops of string format".format(loops))
timeLoops(loops) {
  fmtString.format(replacements(0), replacements(1))
}

println("and again...")
println("running %d loops of string format".format(loops))
timeLoops(loops) {
  fmtString.format(replacements(0), replacements(1))
}

println("running %d loops of string concat".format(loops))
timeLoops(loops) {
  val sb = new StringBuffer()
  both.foreach { case (slice, repl) => {
    sb.append(slice)
    sb.append(repl)
  }}
}

println("and again...")
println("running %d loops of string concat".format(loops))
timeLoops(loops) {
  val sb = new StringBuffer()
  both.foreach { case (slice, repl) => {
    sb.append(slice)
    sb.append(repl)
  }}
}

println("running %d loops of string concat w/ StringBuilder".format(loops))
timeLoops(loops) {
  val sb = new StringBuilder()
  both.foreach { case (slice, repl) => {
    sb.append(slice)
    sb.append(repl)
  }}
}

println("and again...")
println("running %d loops of string concat w/ StringBuilder".format(loops))
timeLoops(loops) {
  val sb = new StringBuilder()
  both.foreach { case (slice, repl) => {
    sb.append(slice)
    sb.append(repl)
  }}
}

Adding string builder benchmark