Was supposed to be fixed with 10.5.10 but clearly isn’t:
I also don’t find anything regarding this in the release notes. I’ts mostly about Mac performance issues, but this is on windows for me…
I think it is actually a bit better in 10.5.0 here. I created a test project with 120 instances of MJUC, up to a load of ~75%, and there’s a bit of a stutter when adding plugins/send, but Cubase was never dropout-free when doing that. Seems OK-ish.
A real life project behaves much worse, even though the load is lower.
So it might actually be specific plugins, but that doesn’t help.