@reinforcez,
the link given by @drakedoc was started over 4 years. Many solutions are given in this thread, and the last one was published a year ago.
That solution works for 1.9 and above !
/* Skip the Gravatar check when using a default BP avatar */
add_filter( 'bp_core_fetch_avatar_no_grav', '__return_true' );
By the way you have also to modify the global WP setting of avatars to “mystery man” or “nothing”.
Another solution to avoid gravatars slowing down a big site (at least > 500 members), is to use a specific cache plugin like Nix Gravatar Cache. Complete list here.
