intermittant hang and crash on tablet and mobile

My wordpress site is intermittently hanging on tablet and mobile phones. It loads 1/2 of the page and then freezes the whole browser until I have to “kill” the browser completely. If I let it hang and continue loading for several minutes, it eventually loads completely and will work and load quickly (as it should). This only happens on tablet (ipad, kindle) and all mobile phones. It works fine on desktop. The only plugin that I have installed is Akismet.

It’s a responsive theme.

If anyone can help, I’d greatly appreciate any ideas.

Thx