Hello there 
As I can see my colleague Alessandro has already suggested those workarounds/solutions that usually would help to solve the slowness issue on Mac (as previously suggested on the other thread), and most cases this’s not related to DevKinsta itself but Docker’s settings.
What if you create a new fresh WordPress site in DevKinta, does it slow as well to open any of that site’s pages on your local browser? If the new fresh WP site’s pages load normally/faster, then most likely something with that specific site that you imported to your DevKinsta.
Regards,
Agus