title: get sub categories from category id Magento
body: <p>i am trying to get sub-categories from category id. 
  but looking for more optimized code as the database vast records and cannot afford to load whole category. </p>
  
  <p>i have tried below codes they are working on localhost but as my server has huge data it doesn't work there</p>
  
  <pre><code>$cat = Mage::getModel('catalog/category')-&gt;load(13);
  $subcats = $cat-&gt;getChildrenCategories();
  
  //AND
  
  $categories = Mage::getModel('catalog/category')-&gt;getCategories($cat_id);
  </code></pre>
  
  <p>please help</p>