+ 1 for "pause" IR. I know this thread has been closed for now, but this feature is really needed. Not just for floating IR but also for viewport IR. I'm mostly (almost only) using IR in a viewport, and the only way to stop or pause it rendering to free up system resources, is to switch view (leaving IR mode). And then the opposite way to activate it. Not at all a quick way.
I think a nice and easy way to do it in both modes, is like most media players do it: click in the viewport, and it'll stop or start, depending on the current status. When in "pause" the well known pause sign [II] could be shown in the render view.
Hope these ideas will find it's way into a great renderer :)