I use a MBP early 2011 just fine.
2,2 GHz Intel Core i7
8 GB 1333 MHz DDR3
AMD Radeon HD 6750M 1024 MB
Intel HD Graphics 3000 512 MB
Must be something different, I guess.
Which OS do you currently run?
Does this happen with all your projects or just some?
Can you try doing a clean install of your software using Use the Creative Cloud Cleaner Tool to solve installation problems , reinstall the software using Creative Cloud destkop app, and let me know if that helped?
I tried your solution, and came up with the same issue. My CPU will go beyond 100% on just a simple scroll or text box move.
I try every solution posed by people on a "busy" project composed of pictures, text and responsive elements AND on a super simple project with only one colored box and a couple text boxes and get the same results.
Anything else I can try to resolve this?
I am still having these issues after talking to customer care. Has anyone who claims that Muse is working "fine" on their MacBook checked to see if CPU ever goes over 100% CPU? I did a system wipe and re-installed. Same issues. I just ran into this youtube video coincidentally showing the same problem I have on my machine. Adobe muse CC 2018 + iMac 2017 lag - YouTube