sclass DoubleFPSCounter {
  new FPSCounter counter;
  volatile double value;

  synchronized void inc() {
    if (counter.secondsSinceStart() >= 1) {
      value = counter!;
      counter = new FPSCounter;
    }
    counter.inc();
  }

  synchronized double get() {
    ret value;
  }
  
  synchronized toString {
    ret counter.isEmpty() ? "" : formatDoubleX(get(), 1) +  " FPS";
  }
}

Began life as a copy of #1033433