Here is the investigation on the results achieved by moving Magento Varien_Object implementation from PHP to C, thus making Varien_Object a PHP extension.
The change is ~3% performance improvement, which depends on use case scenarios, Magento settings and server configuration. The more optimized Magento and server are - the more beneficial the extension is.
Environment configuration used for performance investigation:
- Windows 7 x64
- 4Gb RAM
- 32-bit PHP 5.3.14
- MySQL 5.5.20
- Apache 2.2.21
- APC 3.1.10 for opcode cache
- Magento cache: APC as fast backend, database as slow
- Magento 1.8.1.0
The average time for checkout scenario is 5.15 seconds for original Magento and 5.01 seconds for Magento with php_mage extension. HHVM seems as a better alternative to the approach, because it removes necessity of manual translation of PHP code into C. However, HHVM is not capable of doing intelligent logic optimization.