I will note that Intel CPU Mac devices are slightly underpowered for AI processing and will perform slower. We have some more information on our Topaz Labs Documentation page that I will link below for your review:
You can also try adjusting your AI Processor to run on your CPU. To do this, please open Topaz Photo AI, go to Preferences > General , and set the AI Processor to CPU .
Many users with Intel MacOS machines have reported that Topaz Photo AI v3.0.4 or v2.4.2 is most suited for their needs and experiences, as well as better processing times and consistent edits and displays. I have included a link to that those previous version below if you would like to revert to this version for your machine:
No need to uninstall the current version, you can simply run the previous installer and the current version on your machine will be override.
To address your question regarding a newer Mac, we have lots of users (as well as me personally) report that the M-chip Macs to suite many of the needs for running the application.