I’ve had the same issues and reported it as a bug to Bubble, you should do the same if you haven’t already. This may be part of the performance issues they referred to in their monthly update, but I can’t be sure.
For context, I’ve been building the same app on bubble for almost a year now and only recently had significant reliability issues with the editor and also previewing the app. For me, it only happens on my largest (in terms of workflows and elements) page, yet this page has been the same size for a while and never had any issues up until a few weeks ago. Unfortunately, I don’t have any suggestions as to how to fix it (and I’ve tried just about everything). Good luck! 