Yes theme by default loads many scripts but if you don’t need/use any of them you can disable them (this is in first place a template so use filters, install Child theme and override functions, disable plugins etc.). I can’t tell you how you can optimize your site because I don’t know what content are you using so this isn0t easy task.
I wouldn’t say that our live preview is slow, we just didn’t optimized it. Our live preview runs twice faster then your website and that’s probably because of additional plugins you installed (Events Calendar, WPML, NextGen Gallery, FancyBox..).
I can offer you customization services if you need us to modify/optimize your website. Send us E-Mail if you are interested.