git slow over https

Hi,

I have an apache server that serves git repositories over https. I
have the problem that git is very slow when accessing it, as in 3
seconds for a "git pull" that does nothing.

I tracked the problem down to git sleeping for 50ms using select from
time to time while downloading the response of the server. In my case
this really hurts performance (see attached strace). However, with a
different https server things work quite fine.

If I remove the select in http.c:673 (in run_active_slot), then things
are fast also with my server.

So my questions are:
1) What's the purpose of the select in http.c:673? Can it be removed?
2) If it serves a useful purpose, what can be the reason that it hurts
performance so much in my case?

Best regards,
 Mika Fischer