From what I can tell, it has cleared up the issue somewhat. I don't live in a 4G area but when I used to toggled 4G, my phone would lag and have to be restarted to be usable again. Now, I can toggle 4G, look for a network and have it tell me that there is no connection and to rescan if I want without my phone becoming unusable. I can then turn 4G back off and the phone remains usable with no noticeable lag.. I believe that the new "tap to scan" step has stopped the phone from constantly look for 4G signal, resulting in the lag issue being cleared up. I could be wrong though, I haven't really played with it enough to know if the lag has gone away (I only tried it twice after the update).
I hope this helps.