Your iPhone Is Running More Slowly Than Usual
Even though the iPhone is crazy fast, there will be times when it might start to slow down for no apparent reason.
If that ever happens to you, there are a few things you can try. First, simply restart your iPhone. It might sound like a joke, but it often does work.
You should also try updating your iPhone to the latest iOS release. It’s possible there could be a bug that Apple already fixed. Apple describes even the smallest point releases as including “performance improvements.”
You can also clean up your iPhone storage. Believe it or not, if your iPhone is too full, it will start to run more slowly, so be sure to delete as much useless data as possible. Anything from old screenshots to unused apps might do the trick. If it’s Safari that’s giving you trouble, you can also try clearing your cache and search history. You can do this in the Safari section of your iPhone’s Settings app.
If all else fails, you can always start from scratch by erasing and resetting your iPhone. Keep in mind, though; this will delete everything on your iPhone, so make sure to make a backup before you do it.