Amer:
Begin by adding eaccelerator.shm_size="50" to your eaccelerator configuration. It defaults to 16MB, which is not enough to cache all Moodle scripts.
Also, set Cache initially to None within the Moodle Site Administration block. This is a different type of Cache than the eaccelerator script cache which is confusing. Make sure you restart the server, and let us know if that works.
Look at the eAccelerator memory allocated at /admin/phpinfo.php to see that more memory is being used as more scripts are loaded in eAccelerator. The Memory Size should be more than Memory Allocated. The Cached Scripts count should be approaching 1000.
Page load times should double in speed when using a script cache on average in my experience when tuned right but your results may vary and will depend on the task the page is doing.
Hardware and performance
eAccelerator not being detected by Moodle?
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