I'm running Xcode 7.3.1 on a MBP with OS X 10.11.3.
I started using UIStackViews to help me lay out my UI. The first experiment went fine--made a great custom number pad with it. So I moved to a slightly more complex scene, and once I started nesting stack views, Xcode slowed to a crawl. With every command, it waits 5 seconds, then beachballs for 10 before executing it. Infuriating. I've restarted Xcode multiple times, but no improvement. And I see a number of people have reported this bug to Apple.
I see the beta for Xcode 8 is available, and have read a few comments, but haven't found any directly relating to an improvement in the performance of stack views.
Can anyone recommend the beta as a better choice than my current version based on their experience with stack view performance in Xcode 8 beta?
You should never fully switch to a beta version of Xcode. Apple doesn't yet allow you to submit to the App Store using Xcode 8, and probably won't for some time yet.
Early betas also tend to be full of bugs, rough edges, and performance bottlenecks. In fact, early x.0
RELEASE versions of Xcode tend to be buggy as hell. I wish Apple would slow down their mad rush to add new features and spend time stabilizing the current build tool, but I doubt if I'm going to get my wish.
By all means download Xcode 8 and experiment with it, but don't get rid of 7.3 until after Xcode 8 goes GM, and maybe not even then.