I've had a lot of issues with AppCode over the last year or so hanging a lot. It appears to be getting worse, not better. This hang was after a forced OS security update, and AppCode was attempting to reindex my code. While OS updates are a relatively rare occurrence, these types of hangs happen several times a day, often when I switch Git branches from an external terminal and reindexing begins.
Linked are a spindump and sample of the hang: https://gist.github.com/dwabyick/61bf0607d8df5dc487bd1ef7495b5343