not working... :(
my hosting provider replied
"I am afraid this is not possible as it involves changing the server config globally, the solution shouldn't involve the changing of server settings anyway, it needs to be optimising the query itself to run faster."
"I've had a few of our guys look at the query and they do not think it's possible to optimise, it's simply a bad query. I do not think this query would be part of the standard Wordpress install, so I'm guessing it's a plugin of some kind? it so you could simply disable this plugin and find a better alternative."