Magento Product Cache Loading by Johann Reinke, added "isAdmin" http://www.johannreinke.com/en/2012/04/13/magento-how-to-cache-product-loading/

config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Namespace_Catalog>
            <version>0.1.0</version>
        </Namespace_Catalog>
    </modules>
    <global>
        <models>
            <catalog>
                <rewrite>
                    <product>Namespace_Catalog_Model_Product</product>
                </rewrite>
            </catalog>
        </models>
        <cache>
            <types>
                <product_loading>
                    <label>Product Loading</label>
                    <description>Cache of product attributes loading.</description>
                   <tags>catalog_product</tags>
                </product_loading>
            </types>
        </cache>
    </global>
    <default>
        <core>
            <cache>
                <lifetime>3600</lifetime>
            </cache>
        </core>
    </default>
</config>

Product.php

<?php

/**
 * @see http://www.johannreinke.com/en/2012/04/13/magento-how-to-cache-product-loading/
 */

class Namespace_Catalog_Model_Product
extends Mage_Catalog_Model_Product
{
    public function load($id, $field = null)
    {
        if(Mage::app()->getStore()->isAdmin())
        {
            return parent::load($id, $field = null);
        }
        if (null !== $field || !Mage::app()->useCache('product_loading')) {
            return parent::load($id, $field);
        }
 
        // Caching product data
        Varien_Profiler::start(__METHOD__);
        $storeId = (int) $this->getStoreId();
        $cacheId = "product-$id-$storeId";
        if ($cacheContent = Mage::app()->loadCache($cacheId)) {
            $data = unserialize($cacheContent);
            if (!empty($data)) {
                foreach ($data as $key => &$value){
                    $this->$key = $value;
                }
                unset($value);
            }
        } else {
            parent::load($id);
 
            // You can call some heavy methods here
 
            try {
                $cacheContent = serialize(get_object_vars($this));
                $tags = array(
                    Mage_Core_Model_Store::CACHE_TAG,
                    Mage_Core_Model_Store::CACHE_TAG.'_'.Mage::app()->getStore()->getStoreId(),
                    Mage_Core_Model_Website::CACHE_TAG,
                    Mage_Core_Model_Website::CACHE_TAG.'_'.Mage::app()->getStore()->getWebsiteId(),
                    Mage_Catalog_Model_Product::CACHE_TAG,
                    Mage_Catalog_Model_Product::CACHE_TAG.'_'.$id,
                );
                $lifetime = Mage::getStoreConfig('core/cache/lifetime');
                Mage::app()->saveCache($cacheContent, $cacheId, $tags, $lifetime);
            } catch (Exception $e) {
                // Exception = no caching
                Mage::logException($e);
            }
        }
        Varien_Profiler::stop(__METHOD__);
 
        return $this;
    }
}
    public function load($id, $field = null)
    {
        if(Mage::app()->getStore()->isAdmin())
        {
            return parent::load($id, $field = null);
        }
        if (null !== $field || !Mage::app()->useCache('product_loading')) {
            return parent::load($id, $field);
        }
 
        // Caching product data
        Varien_Profiler::start(__METHOD__);
        $storeId = (int) $this->getStoreId();
        $cacheId = "product-$id-$storeId";
        if ($cacheContent = Mage::app()->loadCache($cacheId)) {
            $data = unserialize($cacheContent);
            if (!empty($data)) {
                foreach ($data as $key => &$value){
                    $this->$key = $value;
                }
                unset($value);
            }
        } else {
            parent::load($id);
 
            // You can call some heavy methods here
 
            try {
                $cacheContent = serialize(get_object_vars($this));
                $tags = array(
                    Mage_Catalog_Model_Product::CACHE_TAG,
                    Mage_Catalog_Model_Product::CACHE_TAG . '_' . $id
                );
                $lifetime = Mage::getStoreConfig('core/cache/lifetime');
                Mage::app()->saveCache($cacheContent, $cacheId, $tags, $lifetime);
            } catch (Exception $e) {
                // Exception = no caching
                Mage::logException($e);
            }
        }
        Varien_Profiler::stop(__METHOD__);
 
        return $this;
    }
}