PC Hardware Performance : Improving Rendering Speed of MOGRTs in 4K

I'm still using the PC I built about 2 years ago, based on i9 9900K processor and ASUS 390A Motherboard.

Quick spec of machine :

CPU is overclocked and locked to 5GHz on all 8 cores - water cooled

Samsung EVO NvME drives

RTX 2070 Super GPU

64GB DDR4 3200Mhz Corsair Vengeance Memory

So - in general now I am  editing in 4K 50fps most of the time and this machine is working well.

No need at all for proxies.

An area I want to speed up is rendering though.

The slow bit is when the timeline gets to some types of MOGRTs.

I am asking a lot from the machne as I am using a hybrid Pro-Res master generation approach where all Previews are rendered in Pro Res so I can generate a fast Pro-Res master afterwards, using the previews during export.

Looking at the Task monitor during rendering in Windows 64 bit - the CPU is only at approx 47 to 49% and the GPU idling along at 19%.

No other major tasks appear to be running. Cache cleaned regularly and Cache sits on a separate fast SATA drive away from system drive.

Latest Windows and all temp files cleaned out regularly and registry checked ok.

So in conclusion, my current machine appears to have more 'oomph' available but Premiere Pro (latest 22.3.1) is not using it?.

Reason I have asked this question is that I was looking at upgrading to a 12900K based machine soon, but until I can understand what is going on with poor rendering speed of these MOGRTs (ones in question are 3D Text zoom in/out with texture etc) then I don't see what an upgrade to 16 cores would do if my current CPU is only at 47%?.

Any explanations  and suggestions welcome.