I'm not sure that the GPU will do much except perhaps free up a little resource if you are running applications in parallel. Ditto huge amounts of memory.
Performance is an odd thing.
I glanced through the link you provided and spotted Gareth's post at the end. That reminded me that my Windows Performance rating had, for some reason, slipped quite a lot the last time I ran the assessment. I was not aware that the system used it to assess how to handle load.
The odd thing was it was disk performance that slipped and the main drive is a fast (for its time) SSD. It had dropped to 5.9.
I re-ran the rating and it is back up to 7.9.
So my GPU capability at 6.6 is not the limiting Windows Experience factor.
I have not yet attempted to compare or asses the latest performance increase - if there is one!
Meanwhile, back to your question.
You could try a test. Make the output a csv file rather than direct to Excel. See how long that takes. For a complete comparison then open the csv in Excel and measure that load time as well.
You could also perhaps export as an Access file (or to Access if you have that option) and see how that goes.
I note that the Technical Specs suggest 4Gb RAM as a minimum, 32bit requirements not excepted.
I'm running Win 7 64bit with Monarch 64bit 24GB RAM, i7 -3820QM @2.70GHz, 512GB SSD as the primary drive.
Office 365 64bit.
Obviously I have no way of doing a comparison test for you but I can say that in general speed seems good. From time to time the system has a "go slow" for a minute or two but that happens with all applications.
The only thing I have noticed consistently with Monarch is that it is leisurely sometimes, notably when switching between Classic and Data Prep modes in either direction.