It was my understanding that HostnameLookups adds latency to only the completion of the request. So a thread that could answer a new request would be blocked until the thread completed the lookup.
However, the Apache documentation reads:
It is also better for the end users because they don't have to suffer the extra latency that a lookup entails.
Does that mean the visitor receives no response data until the lookup is complete? I understand it adds latency to the request, I just don't know to which end, before the response is sent or after.