Speed up stem rendering: auto-mute other tracks whilst doing it

I was rendering some tracks to stems today, and happened to have the Performance Meter window open. To my surprise, it shows that during the render, each track's plugins were being run! This makes no sense to me, as the whole point of freezing things to stems is where you have a situation that the project is using too much CPU and going slow - Reaper should surely auto-mute the tracks that aren't being rendered, so that the rendering happens much faster? (and then un-mute them again when the render is done) (am running Reaper v3.76/x64 on Win7)

obviously +1 guess this is well known issue. hope developers struggle it courageously

Yeah, unless there's something 'under the hood' preventing it, this seems like an easy way to exponentially increase the speed of stem rendering. I'm actually surprised this hasn't been addressed much sooner...