What is the speed different between Standard and Pro Edition?

I have a Standard Edition of World Machine.
A very nice application.
But is is very slow to generate complex worlds.

I have a quad core I7 2600k with 16GB Ram.

How much more speed will I get with the Pro version?

Well, the standard edition only uses to cores or even virtual cores. I would expect that the speed would double.

I would imagine the Pro version would be using all 4 cores of my i7 in some capacity. Thinking of upgrading
myself.

The pro version can multi-thread more completely to use the 4 cores of your machine.

The exact amount of speedup will be heavily dependent on the world you’re building, as not everything can be parallelized, but from 2->4 cores you can expect anywhere between 60-100% faster builds.

Just a question. Do we talk about physical or virtual cores? A Core i7 has 4 physical, but 8 virtual cores.
I work on a dual Xeon with 6 physical cores, each 32 GB RAM and think about upgrading as well. Should be a lot faster with the Pro edition.