1) We have disabled cache plugin that you used and installed W3 total cache. It displays better results than you had.
2) We optimized few slider images to show you an example http://prntscr.com/q3xc95 If you compare the size you’ll understand that you could save a lot of space and speed up your site just by using optimized images because images on the home page take 1.9Mb http://prntscr.com/q3xesk
Use Tinypng online service or WP plugin https://wordpress.org/plugins/tiny-compress-images/
3) Deactivate plugins that you don’t use, Revolution slider for example. Because every additional plugin calls additional scripts and CSS that slows down a site.
