public static DelayPostprocessor getSlowPostprocessor() {
    if (sSlowPostprocessor == null) {
      sSlowPostprocessor = new DelayPostprocessor(20);
    }
    return sSlowPostprocessor;
  }
This is a Postprocessor which just introduce a delay
samples/scrollperf/src/main/java/com/facebook/samples/scrollperf/postprocessor/DelayPostprocessor.java