Does this test build have the same issues?
I see a diference from this and the test downloads from Miller.
When trying to open Miller's I get
"cannot be opened because the developer cannot be verified"
I don't get that when I try to open yours, I get instead I get “Pd-0.50-2-signed” can’t be opened because Apple cannot check it for malicious software.
So it's quite clear signing worked for making it "verified" somehow. That's a pretty clear cue...
I couldn't see any difference in load time when trying your build, but again, let me stress that I don't get it "always" on the build made by Miller, it's something that happens only sometimes and I was also noticing that with my own Pd builds from the repository...