There are a couple more instances of ap_add_*_filter in core.c that can be optimized away using ap_add_*_filter_handle. This particular block is in core_pre_connection().
-Ryan Index: server/core.c =================================================================== RCS file: /home/cvspublic/httpd-2.0/server/core.c,v retrieving revision 1.151 diff -u -r1.151 core.c --- server/core.c 21 Feb 2002 17:20:26 -0000 1.151 +++ server/core.c 23 Feb 2002 08:29:51 -0000 @@ -3841,8 +3841,10 @@ net->client_socket = csd; ap_set_module_config(net->c->conn_config, &core_module, csd); - ap_add_input_filter("CORE_IN", net, NULL, net->c); - ap_add_output_filter("CORE", net, NULL, net->c); + ap_add_input_filter_handle(ap_core_input_filter_handle, net, NULL, + net->c); + ap_add_output_filter_handle(ap_core_output_filter_handle, net, NULL, + net->c); return DONE; }