Zend Guard Performance Problem

Hi, Recently we bought Zend Guard and because of Zend encoder we have to use another Opcode cacher other than APC. After searching net I found eAccelerator. After installing eAccelerator with Zend Guard I saw more than %30 percent performance lost against Normal PHP + APC. Here my setup ;eAccelarator zend_extension="/usr/lib/php5/20060613+lfs/eaccelerator.so" eaccelerator.shm_size="16" eaccelerator.cache_dir="/tmp/eaccelerator" eaccelerator.enable="1" eaccelerator.optimizer="1" eaccelerator.check_mtime="1" eaccelerator.debug="0" eaccelerator.filter="" eaccelerator.shm_max="0" eaccelerator.shm_ttl="0" eaccelerator.shm_prune_period="0" eaccelerator.shm_only="0" eaccelerator.compress="1" eaccelerator.compress_level="9" [Zend] zend_extension_manager.optimizer=/usr/local/Zend/lib/Optimizer-3.2.6 zend_extension_manager.optimizer_ts=/usr/local/Zend/lib/Optimizer_TS-3.2.6 zend_optimizer.version=3.2.6 zend_extension=/usr/local/Zend/lib/ZendExtensionManager.so zend_extension_ts=/usr/local/Zend/lib/ZendExtensionManager_TS.so E accelerator gives %100 boost for normal php and not much as APC. Is anyone have any idea about this ? Any suggestion to another opcode cacher and or Zend Guard options. Regards Sancar