$start_time = microtime(true);
foreach (range(1, 1000) as $id) {
  $node = Drupal::entityTypeManager()->getStorage('node')->load($id);

  if ($node) {
    print_r($node->id());
  }
}
$end_time = microtime(true);
$execution_time = ($end_time - $start_time);
print_r($execution_time);

$start_time = microtime(true);
$ids = [];
foreach (range(1, 1000) as $id) {
  $ids[] = $id;
}

$nodes = Drupal::entityTypeManager()->getStorage('node')->loadMultiple($ids);

foreach ($nodes as $node) {
  if ($node) {
    print_r($node->id());
  }
}
$end_time = microtime(true);
$execution_time = ($end_time - $start_time);
print_r($execution_time);