Ok, tried it in Catalina. Same increase in load time when first loading externals, but this is life now for macOS I guess... nothing to do with signing issues.
Anyway, before releasing the final version, please consider these documentation issues. First, I already mentioned this one
https://github.com/pure-data/pure-data/pull/744 it's just changing ONE word to better depict the actual change. And, as long as we're at it, you may also consider mentioning the change to the number box in the release notes of 0.51!
Also, there are still more manual/html documentation updates waiting in line, see
https://github.com/pure-data/pure-data/pull/720 - Lucas can talk more about that one.
Now, as for a last minute request, out of almost 100 waiting in line, I was hoping to get your attention to at least one request, and I feel comfortable about it because it's really a no brainer, and I kinda need it to release an update of cyclone - see
https://github.com/pure-data/pure-data/pull/899 - basically, I was hoping Pd could ship Deja Vu Sans mono in full, cause I wanna use it as the default font for cyclone/comment, which also allows you to load italic and italic+bold. It turns out I can't just ship fonts as part of cyclone myself, so I needed Pd to ship that for me.
Cheers