I just did a Pro training course. For simplicity, I took our (admittedly elderly) dual 2.2GHz, 4Gb Windows 10 laptop. This has run Desktop (many versions) perfectly fine for years along with a suite of other GIS/DB tools, and seemed to work okay with some basic testing of Pro after installation.
Once I loaded up some tutorial data for exercises, it was agonising. 99+% CPU usage, most of the GPU and perilously close to thrashing page file (I shut down everything possible to shut down in Windows) running consistent 1.5-2GB RAM usage. It was basically unusable, 1-2 minute waits to do anything in Windows, and I could see Pro literally rendering every object second by second.
Sometimes it just gave up and said "meh, close enough for government work"
This was with a few tiny tutorial datasets and the web basemap/hillshade.
I didn't even dare trying 3D seeing as Pro was unable to even handle a file explorer dialog. After falling further and further behind the class simply because Pro does not run on a Desktop-capable computer, I gave up and ditched it for my workstation (2014 quad 3.4GHz, 16GB) for which is was fine, although the NVidia Quadro struggled a bit with frame rates in dynamic 3D.
Looking at what it was doing, I think Pro is spinning up a large number of background processes/services which eat up resources (geoprocessing handler, job handler, etc.) I could also see it dynamically building displays, panes and elements, sometimes rejigging them in real time as things opened and changed to get the desired layout, so there is a lot of work going on under the hood which is much more demanding and sophisticated than Desktop. Every time you click on something it is running through a whole set of rendering/workflow/data management dependencies.
For example even something simple like opening an attribute table. In Desktop, bang, open pane with first X lines, done. In Pro it was doing some kind of indexing, analysis, calculating different font sizes, column width etc to make it all 'look nice' before opening the table, and then of course depending on docking it had to resize multiple other objects and re-render them as well.
Short story: Unless you have a fairly new computer, expect that you will have to upgrade it to run Pro.