I can't answer as to why PECL will affect your page load times. But regarding the installation of PECL to your PHP installation Google is your friend.

I found this link How to install a PHP PECL extension/module on Ubuntu

PECL extension in Ubuntu 11.10
Hi If magento fails to run the log cleaning process as per the configuration then where it does saves the error_log (or) failure status? Magento doesn't clean the log tables periodically.

Note: I can't set Cron from cpanel(WHM) to do this automatically, as I don't have option.

Any help will be appreciated 

Thanks
