Thanks for the replies!

1. Good to know, I'll keep this in mind for when I'll have a bottleneck in http parsing/throughput.

2. OK so curb now yields on fiber IO where it previously did not. Got it!

3. I was referring to Ractors, the experimental Ruby’s Actor-like concurrent abstraction: https://docs.ruby-lang.org/en/master/ractor_md.html

Ah - thanks for the link. Now I have maybe another thing to see if we can improve in curb to ensure Ractor is fully supported. (it might be i just have not tried)