Maybe for once I got my financial timing right
I was getting to the stage where I was having to seriously consider paying for something like Topaz for noise reduction.
What I can say is in the Group I meet every 2 weeks to discuss mainly computer issues my Mac LRC denoise performs much faster with 45 MP files than Topaz does with files from lower MP cameras using PC's - clarifying nothing unless the PC and Mac have similar specifications.
I expect in about a months time the Group will compare Topaz denoise with Lightroom denoise.
LRC denoise may be only a little beyond beta development - with improvements promised over the coming months.
Topaz may also up their denoise performance.
The spec of the Mac desktop that I use is 12 core CPU, 38 Core GPU and 16 Core Neural Engine that to some extent work together.
I expect a lesser LRC denoise performance from my 4 year old 27 inch iMac when it returns from repair next week.