For Keyless SSL, it is necessary to make RSA operations asynchronous, since the operations are requested over the TCP network (which may have big delays).
OTOH Neverbleed degelates the operations within the same server using Unix sockets. So there is no fear of such delays. And the server spawn a dedicated thread to each client thread. In other words, the delay is practically _no worse_ than what it is without Neverbleed.
And discussing _how worse_ it is, calculations related to TLS handshakes may block the server for a few milliseconds. It may sound bad, but generally speaking it is negligible comparing to the latency over a public network.
For Keyless SSL, it is necessary to make RSA operations asynchronous, since the operations are requested over the TCP network (which may have big delays).
OTOH Neverbleed degelates the operations within the same server using Unix sockets. So there is no fear of such delays. And the server spawn a dedicated thread to each client thread. In other words, the delay is practically _no worse_ than what it is without Neverbleed.
And discussing _how worse_ it is, calculations related to TLS handshakes may block the server for a few milliseconds. It may sound bad, but generally speaking it is negligible comparing to the latency over a public network.