Based on your description my first guess would be a known slow-down on macOS 10.14. Try and see if you experience the same with the same file on a different computer with an earlier version of macOS. If it is faster, then you may have ran into this issue: https://helpcenter.graphisoft.com/knowledgebase/75345
Also, regardless of whether this thing helped, make sure to check all the other Mojave related known issues here: https://helpcenter.graphisoft.com/knowledgebase/84821/
If you are still having issues after this (and indeed with this single project and nothing else), then send it to your local support for further inspection (or if you can't, then I may be able to check it too).
PS. You can do a screen recording with Quicktime, that should record things properly.... I think....
Daniel Alexander Kovacs
Professional Services Consultant
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