I have found that you need to be a little careful about how complex you build field groups. On of the sites I build the client needed to ability to add multiple section to page. Each section could have up to 7 WYSIWYG editors. Each of these editors also had various layout controls for borders, padding, font settings, etc. This worked fine at first by then the client added a page with 20 sections, that’s 140 WYSIWYG editors. The update process timed out. There really isn’t a solution unless someone comes up with a way to update all of those fields in the postmeta table in a single query rather than one at a time.
As far as getting information @gecugamo is correct. When using image fields you’re better off returning the ID and then doing the work yourself. ACF building of image objects is a serious drain and can take a long time, especially if you have a lot of custom image sizes.
