I am fairly certain that I experience the same latency issue with right-click context menus in Windows Explorer as what you have described.
I was hopeful that the recent acquisition of a new machine with a fresh WIN10 install on it would provide me relief from this issue -- but the situation is unchanged with the fresh install.
Your research shows me that the underlying situation and cause is hardly something that "I am imaging" -- this is an ugly piece of mis-performant code.
Perf also lacks a powerful UI like WPA. But, perf is pretty amazing in its own ways.
Instead they appear to have been dependent on anecdotal evidence and nobody taking responsibility.
Or maybe I'm wrong. Maybe this action was instrumented but was then ignored. That would be sad.
Perftrack reference: https://channel9.msdn.com/Blogs/Charles/Inside-Windows-7-Rel...
alas understanding is completely removed from the equation.
Why does the average person buy a computer ?
my small sample say "no more post office, everything is online, so I .. need something"