Hi all, thanks very much for this work.
I'm testing on Catalina 10.15.5. I installed Pd-0.51-0test2 when I had System Integrity Protection and Gatekeeper disabled. I got an initial warning asking if I wanted to open the software, and a request for microphone access the first time I turned on DSP. Also got a dialog confirming that I wanted to allow network comm when loading a patch with [netsend]/[netreceive]. After that, I've had no issues, and all of the externals I've tried so far are working with no increased load time that I can notice. I've used ofelia, tof, hcs, timbreID, and a DSP extern of mine for a current project - all working fine.
Since that initial run I re-enabled SIP and Gatekeeper to see if that would affect performance. After reboot, it brought up the above warning/confirmation dialogs again, but then no problems and still no increased loading times here.
PS: I happen to have a project that involves lots of TCP messaging between remote networked players and we're meeting twice weekly these days, so I can look for any issues related to network performance. And I'm happy to test/confirm any specific details of this release - I have the blessing/curse of 3 separate machines running Ubuntu 18.04.4 LTS, Mac OS Catalina, and Windows 10.