I am by no means an expert, but i have been testing a few things out when hardware and software is concerned when rendering as this cpu/gpu is an age old question.
if you are dealing with 3d projects you need a better than decent gpu, the cpu will only carry it so far until it simply will struggle. i believe for content such as 3D you do need to look at the quadro cards as they are built for such projects., you also need to up your game with your memory, cpu, as both still lack in the power rankings. also look at the "hard" drive ie hdd /ssd, if your main drive and the drive your files are on are HDD you then need to upgrade to ssd.
also have a look at your sequenc settings as changing it down to 720x for previewing instead of full 1920 WILL help previewing and processing power.
also ensure the system is fully defragged with a programe such as Auslogics DiskDefrag
Well, to be blunt: Forget it! You are wasting your time and looking in the wrong place. Simply buy Element 3D. If you are using a Mac, you are on the losing side no matter which one - as long as Apple and nVidia don't have a handle on the graphics driver and the specific model isn't supported by AE, none of that does you any good. And that raytrace 3D stuff is crap to begin with. What good does it do you, if a new Mac cuts render times in half, when even the most unsophisticated 3D program or 3D plug-in still renders at least 10 times faster? Again, you are trying to solve your problem on the wrong end. With that money for a new Mac you could buy all the 3D plug-ins out there and beef up your workflows much more than with any new hardware...
OK just seen Element 3D video and I think it is really impressive. But I don't clear if it is only an importable 3D objects library or if this plugin will increase the speed in my mac too.