Hello friends, has anyone implemented the cache settings? There is a configuration instruction in osclass, it is said to add the line define('OSC_CACHE', 'apc'); to the config.php file.

and also write

define('OSC_CACHE', 'memcache');
   $_cache_config[] = array(
       'default_host' => '127.0.0.1',
       'default_port' => 11211,
       'default_weight' => 1
   );
Where 'default_host' => '127.0.0.1' is the IP address of the server where Memcached is installed.

So, I'm wondering if there is an improvement in the operation of the site from this, is it necessary at all?

I use this one:
define('OSC_CACHE', 'memcache');
$_cache_config[] = array('default_host' => '127.0.0.1', 'default_port' => 11211, 'default_weight' => 1);

Looks same, depends on hosting.
Improvement should be that some queries are cached.
You can measure when enabled database debug log, not all queries are always executed against database.