Slow(er) frame rate with 3.1 on El Capitan

(Repost) I found that Renoise 3.1 had slower framerate than 3.0 on my Macbook Pro running El Capitan: the spectrum analyser and the master volume VU meter (and the rest of the GUI of course) don’t go beyond 20 fps, unlike Renoise 3.0 which could run at 60 fps on the same machine, even at 80% CPU usage.