If your iPhone or iPad is running slow, it’s probably either your Internet connection or all those tabs you still have open. Thorin Klosowski, Lifehacker, reports that iPad Insight points out that you can just enable private browsing. Tap squares in the bottom right of Safari (or + on the iPad) and then hit the “Private” button in the bottom left. Choose “Close All” on the popup. Tap “Private” again to return to normal browsing.
It seems like a lot of steps, but it’s easier than all that swiping or deleting every open tab.