This test was an apples to apples comparison of a moderately noisy image with a sharp subject. For me, the winner is Topaz by a somewhat narrow margin. The reason behind this win, is that Topaz has better noise to sharpness algorithms than Lightroom. The second reason is speed. Lightroom was unacceptable in this area. I am running no junk PC either. This has fast, 6 core Xeon processors (overclocked) , with a 6 gig Nvida graphics card (overclocked) and 32 gigs of RAM.
As long as we are on the topic of performance, the Topaz software uses your GPU to make it even faster. I noticed very little GPU usage from Lightroom.
The remaining noise (after correction) in Lightroom seemed more natural, while topaz is clearly going for clean and noise free. This is a subjective topic for sure. Which one do you like better?
For those who own Lightroom and you are doing this type of image work, then I think Lightroom will work with a little sharpening after the fact. If you want to step up to Topaz, you have a much stronger AI toolset than just denoise. The reality is, that Topaz combines all of these into Topaz Photo AI now. Meaning, Topaz it is faster and easier to use for professional photographers , who are batch processing images.