Frozen

Since recent IPhone upgrade to latest IOS 11... - Adding or deleting a symbol to one of my watch lists caused it to freeze and not scroll through the list.   Tried deleting the list and re entering positions but froze again.  Also very slow to load data such as 52 week high/ low, yield etc. - sometimes won’t load at all within a reasonable period of time.  Loved the old version of the app - please offer ability to revert?  Not sure what new version was supposed to improve?