Agile boards in Jira 8.0 will get a lot of performance improvements. To know, what exactly had changed - read our blog post about performance changes in Jira 8.0. If you still have questions - it is a perfect place to ask them here.
Classic chicken or the egg problem. Need to link to a Developer Community thread in the blog post and you need to link to the blog post in the Developer Community. That’s what you saw this thread this morning. Our apologies for the confusion.