Are you building your own binaries in both cases?
yes
What polling mechanism was RHEL 6 using? You can see it in the ./configure output: "Using 'epoll' polling system"
from config.log: Using 'epoll' polling system with CLOEXEC _______________________________________________ zeromq-dev mailing list zeromq-dev@lists.zeromq.org https://lists.zeromq.org/mailman/listinfo/zeromq-dev