disable-magento-logs.xml

<?xml version="1.0"?>
<config>
    <frontend>
        <events>
            <!--disable logs-->
            <controller_action_predispatch>
                <observers><log><type>disabled</type></log></observers>
            </controller_action_predispatch>
            <controller_action_postdispatch>
                <observers><log><type>disabled</type></log></observers>
            </controller_action_postdispatch>
            <customer_login>
                <observers><log><type>disabled</type></log></observers>
            </customer_login>
            <customer_logout>
                <observers><log><type>disabled</type></log></observers>
            </customer_logout>
            <sales_quote_save_after>
                <observers><log><type>disabled</type></log></observers>
            </sales_quote_save_after>
            <checkout_quote_destroy>
                <observers><log><type>disabled</type></log></observers>
            </checkout_quote_destroy>
        </events>
    </frontend>
  </config>