eAccelerator is used improve performance of PHP scripts by caching them in their compiled state, so that the overhead of compiling is almost completely eliminated. It also optimizes scripts to speed up their execution.
If  eAccelerator is installed on serverwide then it is enable for all account or you can enable it eAccelerator by makeing  a .htaccess file in your ‘htdocs’ directory, and add the following lines:

php_flag eaccelerator.enable 1
php_flag eaccelerator.optimizer 1

if you’d like to turn off eAccelerator for a particular directory, put the following in a .htaccess file in that subdirectory:

php_flag eaccelerator.enable 0
php_flag eaccelerator.optimizer 0

If php suexec is enabled on server then create php.ini file and following code in that file to disble eAccelerator.

eaccelerator.enable 0
eaccelerator.optimizer 0

Regards
Alex P
System Administrator