This is how I'm calling the ops. I use the stats object which is a Summary to get the timing.

gistfile1.scala

val maxOp = Histogram(tileSet, polygon, tile)
Demo.server.getResult(maxOp) match {
  case Complete(median, stats) => {
    (id,median.getMedian,stats.stopTime - stats.startTime)
  }
  case _ => (-1,geotrellis.NODATA,0L)
}