Magento - load only configurable products

I have the following code:

$_productCollection = $this->getLoadedProductCollection();

foreach ($_productCollection as $_product)
{
  if ($_product->_data['type_id'] == 'configurable')
  {
    ...
  } 
}

While it does what it's supposed to do, it greatly slows down page load time. Is it possible to load only configurable products and remove the check for 'configurable'? The store has 12000 products, about 700 are configurable and the rest are child simple products.

I found the following code which returns all configurable products. I need only the products within the current category:

$collectionConfigurable = Mage::getResourceModel('catalog/product_collection')
                ->addAttributeToFilter('type_id', array('eq' => 'configurable'));