We will not install Zend Optimizer:
1. Download the setup of Zend Optimizer from
Here and save it on the server.
2. Run Setup and Click Next on first screen of the installation.
3. Accept the License and Click Next.
4. Select the installation directory as %plesk_dir%\Additional\PleskPHP5\extras to avoid permissions problems as Plesk sets deny permissions to psacln and psaserv on "Program Files".
(where %plesk_dir% is the Plesk installation directory)
5. Select the browser as IIS.
6. Select php.ini path as %plesk_dir%\Additional\PleskPHP5\
Continued...