https://issues.dlang.org/show_bug.cgi?id=20219
--- Comment #2 from Rainer Schuetze <[email protected]> --- I've been bothered by the idle CPU time recently too. Not sure what to do about the additional threads staying around forever, maybe they could terminate after some time of not running, but that adds considerable overhead when restarting them. It seems that the parallel marking has worked out without much troubles (better than expected). When making it opt-in, only few programs would actually benefit from that, because people won't bother to change the defaults. --
