So the culprit appears to be new calls to
fmaf(), floating-point multiply and add. The standard library version uses way more processing power than the built in operators. No surprise, since the compiler converts them to a single-instruction VFMA (floating point multiply and accumulate) operation.
I've deployed a new version (also updated to Heavy release 2017.2) on the server and pushed to the
master branch of OwlControl. With this, Cloud Delay runs with 52% CPU.
I don't know when exactly the change happened and if it was done on our side or Heavy, but if you've had poor performance from your Pd patches recently then pls try recompiling and see if this update improves it.