> A new pid is always more than the previously assigned pid during an OS uptime[1]

This is not universal. Pids can be reused in unixes. The footnote seems to be missing when I went to see if it provided this context.

> Signals are plenty fast. Cloudflare benchmarked 404,844 1KB messages per second. That can suit most performance needs.

Uh, how is Cloudflare sending 1kB messages with signals? Neither this article nor the linked Cloudflare post seem to elaborate on this.