this is not universally true, it depends on the plugin (some don't smart disable at all, regardless, some only do it after all processing is done) 2) you can smart disable everything, then selectively exempt various plugins in the individual wrapper menus, so anything that's glitchy under universal smart disable can be taken back out of it one by one. In sum: no, there is no drawback-- it's a great cpu saver. I think FL doesn't turn it on by default because it does make some vsts glitch out (unwantedly), and maybe also because the reverb tail thing has been true for some plugins in the past. Also yes, it's turned off automatically for rendering.