On a RoonOS machine, like Nucleus or a NUC running ROCK, more RAM will never speed up anything.
This is not true in Windows, MacOS and most Linux distributions, where RAM may speed things up. They have a file on disk where they offload RAM in certain situations, but RoonOS doesn’t have that at all.
If you run out of RAM on RoonOS, Roon will crash, so adding RAM can prevent that crash, but it never ever can improve performance.
Higher is not better, but too low is bad. I’ve written about this here:
The summary is that the number is good for knowing when things are bad but not for comparing how much better or worse the 2 situations are against each other. The reason is that more advanced CPUs self-throttle so they can run slower when the workload is less intense, and you can’t really know when that’s going to happen.