Build a Website

We have recently migrated our website to a different theme (Eleven - by Clapat) with Wordpress CMS. Although the website is working fine, we need slight changes in the PHP to customize the total experience and make it faster. The work will entail issues like arranging text on the website page headers, working out the newsletter plugin into the site, etc. Looking not just for a coder but an experienced freelancer who knows about the cause and effects of different changes in the website design and response of the website.