Block Caching

To cache a block individually, add this method to the blocks class:

Copyprotected function _construct()
{
    $this->addData(array(
        'cache_lifetime' => 3600,
        'cache_tags'     => array(Mage_Cms_Model_Block::CACHE_TAG),
        'cache_key'      => 'CACHE_KEY',
    ));
}

Note - if you set cache_lifetime to 0 (or any other value which PHP evaluates to false) then the cache will actually last 7200 seconds (2 hours), so in order to have a very high cache time then the cache_lifetime should be set to anything up to 9999999999 (about 317 years)