Problems on your website starts when max page width is under 767px and you are in the home section of your page.
Than my Firefox starts showing notice "A web page is slowing down your browser".
The tab with width over 768px is working normally where the other tab with smaller width just hangs.
Try to disable that slider module you are using, to see if the problem stays.
As if I load some other page other than home, the problem is not there and site works normally,
but when going back to home, the problem reappears so it must be something with the home page and most likely with the slider.