Mongrelもthinもkeep-aliveしない

今迄知らなかったんですが、Mongrelもthinもkeep-aliveしないで強制的に "Connection: close" しちゃうんですね。理由は以下のように書いてありました。

You may also work the HttpResponse object directly using the various attributes available for the raw socket, body, header, and status codes. If you do this you‘re on your own. A design decision was made to force the client to not pipeline requests. HTTP/1.1 pipelining really kills the performance due to how it has to be handled and how unclear the standard is. To fix this the HttpResponse gives a "Connection: close" header which forces the client to close right away. The bonus for this is that it gives a pretty nice speed boost to most clients since they can close their connection immediately.

http://mongrel.rubyforge.org/rdoc/classes/Mongrel/HttpResponse.html

パイプライン化が速度を低下させるんですか、実装が複雑になるから？それはともかく、パイプライン化をあきらめたと同時に Connection: close ってのもなかなか大胆な決断だなぁと思いました。keep-aliveの実装も速度低下するんでしょうか。いつか実験してみたいと思います。