Hi BigCapitalist,
Maybe you are also interested in this article from Puget Systems about
AgiSoft and CPU Performance.
Even though you can see improvements rising both clock speed and threads, at the end of the day, higher clock speeds turn into shorter processing times. In fact, you can see in the article how an AMD Threadripper 1950X with 32 threads is almost always beaten by, for example, an i9-7900X with "just" 20 threads but higher clock speeds.
Also, take @SAV 's advice into account. Sometimes, if you are in a budget, it will be better to buy a second GPU rather than spending $1K in a new CPU.
I hope you have now a bit more information to make a better decision.
Best,
ArnauCM