Thats like asking why and how much does an apple make your doctor happier than if you eat a candy bar.
It depends on pretty much everything else in your system.
More ram is less time spent shuffling data around.
On low end systems, a sudden demand for a mess of data from storage can bottleneck work that would have been running smoothly on a system with more ram or more speed overall.
There is no exact answer, but more is generally not a bad thing.
Think of it like this, if you can hold more information in your brain, you don’t have to google everytime someone asks you the airspeed of an unladen African Swallow because you have that already in memory. If you have to go look it up because its not in memory, you’re slower.