The ssl module sets a "debug" flag on the OpenSSL SSL struct at the end of PySSL_SSLdo_handshake(): self->ssl->debug = 1; The OpenSSL header files have this to say about this flag: /* set this flag to 1 and a sleep(1) is put into all SSL_read() * and SSL_write() calls, good for nbio debuging :-) */ int debug; Some uses of it in the OpenSSL source are actually guarded by a macro (#ifdef PKT_DEBUG), but some are not. Bill, do you remember why you put that call? I would find it strongly preferrable to remove that assignment (doing so doesn't seem to break anything in the test suite).