Woo Commerce Wordpress update & repair

After recently applying updates to [login to view URL] , Jewellery WooCommerce Theme ID: WCM010017 the website developed problems. Now The cart box on the homepage configures slowly on initial website loading, Also There are 5-6 second delays between selecting to view item detail or to add to the cart. I have been told I cannot use the newest woo commerce updates as they will break the customized site. I want to be able to update the underlying woo commerce module with the most current. This will require some change to my check out sequence. I want to hire someone who already knows how to do this modification of a Wordpress site using woo commerce to make it as fast and simple as the most current woo commerce demo examples. I lost the ability to search by color. The website must continue to work responsively as well (as it does now). I request responses from the person who will actually do the work. I request sales people for their company NOT respond. Thank you so much! SUMMARY: SPEED UP: 1. initial site load 2. selecting to view detail 3. selecting to add to the cart. UPDATE: : *** Woo commerce Data and Template file update to latest version 2.6.9 while NOT breaking or injuring customized site. *** Update PlugIn Yith Woo commerce multistep checkout premium *** Update Wordpress to 4.7 *** Fix ability to search by color *** Maintain Fully responsive (look at current responsive site before making changes)