It is ridiculous that this problem exists in wordpress for so many people. I was having the same problem.. and will probably continue to have this problem.. Every time i add multiple photos or the number of my characters is too big I get the red lines in my visual editor just like you. The only solution that i have found is recreating that page and using less words or photos or smaller sizes of photos. It is extremely frustrating and shouldnt even be a problem let me know if there is a solution to all of this..
