Hi, I don’t expect you to be interested in this but I thought I’d mention it as I’ve just lost 2 weeks of productivity to the developers of this plugin -https://www.wpmapspro.com
They state that a ‘lazy load’ function associated with Cornerstone is the cause of the problem. When a map location is added to a post via their plugin or in Advanced Custom Fields, then their map is added to the post using shortcode, upon saving, most of wordpress becomes unresponsive. They are adamant that Cornerstone is to blame as when it is de-activated, their plugin works.
Now I guess I am back in that ridiculous Wordpress game where each developer blames the other, neither produces a fix and I end end up losing money.
Just thought I’d mention it but I think I already know what you’re going to say…