If you switch to using prepare_cached for the xbind version, it should make a difference. It would not be possible to use prepare_cached for the xinline version in most cases, since that would results in a new query being cached and held in memory for every possible value of id. Also, you should actually do the variable substitution in xinline to make this realistsic, i.e. "id = $id".
Comment on Re: Re: mod_perl was hosed by a bind variable
I know that prepared_cache would make a big difference, but I wasn't interested in testing that, just the queries that were shown in the root node.
Thanks for pointing it out though.