Hello guys,
Cubase 8 has shown and proven to offer slightly better performance than previous versions. That is a fact.
I won’t start a discussion about ASIO Guard 2 should be active or inactive in your system. That is something that you need to decide by yourself individually as we are talking about individual setups, especially in studios or if you are working on huge projects.
My experience with cases where people use a non-simple setup (such as big studios) is that they will probably get rid of many issues only after setting up Cubase from Scratch or resetting the preferences.
Please try at least safe start mode and then let us know how your experience was. By comparing both results (with and without preferences) it will be easier to help you troubleshooting issues.
All the best,