Solidworks and Autodesk Revit to answer your first Q. We can also throw in virtual machine hosts and SQL. There are many, many others once we get into modeling and scientific applications but you'll have to do your own research.But only the 16 cores of the 5950x ??? Name two.
The 5950x and the 7950x will have two ccx so they have inter-core lag just as much and if you look at the clocks of the 5950x core coherency is just as bad on the 5950x with single core clocks being about 33% faster then when all 16 cores are running.
Regarding the two CCXs - this is true. There is definitely an extra latency introduced with the IF.
However, the major difference between AMD's IF and Intel's E-cores is that, on the other side of the IF, you have more P-cores that are just as powerful as the first CCX. What do you get on the other side of the latency hit introduced by Intel's E-cores?? Eunuched cores (E-cores) that only act as an anchor to the P-cores much of the time. Again, we'll see if Intel corrected the issue with the Raptor chips in about 5 weeks.