https://bugs.winehq.org/show_bug.cgi?id=28412
--- Comment #4 from jbh@alchemy.lu --- AFAIK, it can safely be closed. The issue in the bug does no longer exist. There is no higher cpu use when enabling Native Events (I assume that some fast path was implemented), there is however a drawback in doing so, as sometimes the audio threads will have to wait on an event due to congestion in the wineserver, and you will get an audio under run that you won't get with the parameter disabled.
Reaper does use a lot of cpu to draw the gui, but that is unrelated to this bug and will hopefully go away some day :)