CakePHP lean controller method that gets called multiple times per minute

Is there a way in CakePHP to create a "lean" controller method?

I'm planning to call a controller method multiple times per minute for each user via a simple ajax call. The method just returns a simple value out of memcache (current active users on site). I would like to know if there is a way to create a lean method without any overhead as this method will be called around 10.000 times per minute.

I tried implementing this with a NodeJS-broadcast which worked to some degree but wasn't entirely reliable.