@mercime
==== this has been resolved in upcoming BP 1.6===
WP 3.3.1 Network with WPMU Domain Mapping plugin
BP 1.5.3.1
bp-custom.php – define ( ‘BP_ROOT_BLOG’, 3 );
whenever default BP admin bar is disabled (or not served to not-logged-in users), the following non-existent link appears in source for all sites throughout the network:
/wp-content/plugins/buddypress/bp-themes/bp-default/_inc/css/adminbar.css?ver=3.3.1
… this adds full 3 seconds to page loads.
also, the following appears no matter what in source of all sites:
/wp-content/plugins/buddypress/bp-themes/bp-default/_inc/global.js
if you need help testing version 1.6, drop me a line, glad to help.