Hey,
I do not think it is related to lags. It does not happen always but often. Maybe 1/5 of all clicks.
I made some video:
On second 11 you see like I click on emitter module and nothing happens. menubar is just blinking.
On second 23 you see how I try to edit some value in details panel and module gets deselected.
Like i said it does not only happen in cascade but not very often in other parts of editor.