protected function startMetrics($behaviorSlug)
    {
        $metrics = $this->metrics;
        $bucketIndex = $this->bucket->getIndex();

        // Increment counters
        $metrics->increment('Features', $behaviorSlug);
        $metrics->increment('Buckets', $this->keys[$bucketIndex - 1], $behaviorSlug);

        // Start timers
        $metrics->startTiming('Features', $behaviorSlug);
        $metrics->startMemoryProfile('Features', $behaviorSlug);
    }