MOTUnation.com

I have sent MOTU my Mac's system report, a project file containing the movie file, and a movie file capturing the screen that slows down when the movie is inserted.
I am waiting for a response from MOTU.

Thanks for the valuable technical information!

I'd like to think the Mac Pro 2013 is still new, but ... . I hope MOTU can solve this problem. Until then, I will continue to use DP10.13.

I reported the issue to MOTU via my Japanese dealer. The Japanese dealer says, "MOTU is currently investigating this issue, but we expect the problem to be specific to older Mac Pro."

I live in Japan and need to make a product registration request for DP11 upgrade to MOTU from my distributor in Japan,
and have already requested it. However, my account is not yet listed for DP11 upgrade,
I will report here once I get a support ticket for DP11 and get a reply.

Thanks for the advice!
I will contact MOTU TechSupport.

I am also suffering from the delay in response time with DP11. It only happens when using movie. I'm using a Mac Pro 2013 12core with Mojave OS and Vienna Ensemble Pro at the same time, but the same thing happens with DP11 alone. In the same environment, with DP10, the problem does not occur at all.