With respect, there is the possibility that a plugin developer may have some code that might not play well with the new UI in Cubase 13. It might not be entirely Steinberg’s fault, as we can not know whether any particular developer has played 100% by the rules.
– agree entirely, this has also been my experience over decades.
I also have one (last) VST2 plugin which works fine in C12, and even works fine in C13 until I open the UI of the plugin; luckily, it doesn’t cause ASIO spikes, but I’m going to have to find an alternative.
My point is this: in the interest of finding the root cause, is your issue reproducible in a project that does not use any of the plugins in your initial example project, in the video at the top of this post?