It's a bug: http://core.trac.wordpress.org/ticket/11831 More Solution performance - Do deactivated plugins slow down a WordPress site? in WordPress customization - Can I disable the auto complete? in WordPress design - How to create a new theme from scratch? in WordPress Should a SEO plugin be necessary? in WordPress headers - How does one suppress a 404 status code in a WordPress page? in WordPress Reffered: https://wordpress.org/
