If Loader is your only bottleneck, you must have way too many external dependencies. I often see projects with dozen of external libs where people just use the way they're used to from other frameworks. The end result - you're not using Phalcon but Laravel or Symfony framework (performance wise).
OPcache should be your only out of the box solution. Phalcon loader when used properly is the fastest available loader in the PHP world (alongside SPL autoload).
Just avoid any includes / requires and use namespaces or classes strategy.