xmlrpclib is using the old HTTP and HTTPS classes from httplib which are to quote the docstring, "Compatibility classes with httplib.py from 1.5." and force the use of HTTP 1.0. This prevents connection reuse and pipelining. Attacked is some code we are using as a workaround. Is the xmlrpclib in the standard library required to keep compatibility with old python versions?
There is already a patch for using HTTP/1.1 in xmlrpclib: http://bugs.python.org/issue1767370 There is also another open issue related to this, so the best to do here is some "merging" of issues and patches and leave just one of them open.