https://github.com/phalcon/zephir/issues/756
https://blog.phalcon.io/
Deprecation for PHP 5.3
Phalcon 2.0.x is the latest series of releases supporting PHP 5.3 (>= 5.3.21). Due to this constraint, we were unable to include some performance enhancements to the framework.
From 2.1.x onwards we are deprecating support for PHP 5.3. We highly encourage developers to upgrade their installations to 5.6, since PHP 7 is just around the corner. We are working on PHP 7 support for Phalcon, but in the meantime the recommended PHP version with Phalcon is 5.6.