4 second (!) MySQL location views queries

I have some pages that use location and views that are taking over 30 seconds to render. For example, see http://autism.healingthresholds.com/therapist/us/new-york/new-york/ny/all/25. That loads fast because I'm using boost cache to save the html. But for the initial page generation, devel says that there are multiple queries that take over 6 seconds.

Here's one of them:

SELECT DISTINCT(node.nid) AS nid, node.title AS node_title, node.vid AS node_vid, node_data_field_body.field_body_value AS node_data_field_body_field_body_value, node_data_field_body.field_body_format AS node_data_field_body_field_body_format, node.type AS node_type, location.lid AS location_lid, node_data_field_list_image.field_list_image_fid AS node_data_field_list_image_field_list_image_fid, node_data_field_list_image.field_list_image_list AS node_data_field_list_image_field_list_image_list, node_data_field_list_image.field_list_image_data AS node_data_field_list_image_field_list_image_data, node_data_field_list_image.field_list_level_value AS node_data_field_list_image_field_list_level_value, node_data_field_list_featured.field_list_featured_value AS node_data_field_list_featured_field_list_featured_value, (IFNULL(ACOS(0.757556530858*COS(RADIANS(location.latitude))*(0.275695572132*COS(RADIANS(location.longitude)) + -0.961245000771*SIN(RADIANS(location.longitude))) + 0.652769563134*SIN(RADIANS(location.latitude))), 0.00000)*6368998.45727) AS location_targeted_proximity_sort FROM node node LEFT JOIN location_instance location_instance ON node.vid = location_instance.vid LEFT JOIN location location ON location_instance.lid = location.lid LEFT JOIN term_node term_node ON node.vid = term_node.vid AND term_node.tid = 3494 LEFT JOIN content_field_body node_data_field_body ON node.vid = node_data_field_body.vid LEFT JOIN content_type_listing node_data_field_list_image ON node.vid = node_data_field_list_image.vid LEFT JOIN content_type_listing node_data_field_list_featured ON node.vid = node_data_field_list_featured.vid WHERE (node.type in ('listing')) AND (node.status <> 0) AND (location.latitude > 40.3887981129 AND location.latitude < 41.1126858871 AND location.longitude > -74.474310416 AND location.longitude < -73.518749584) AND (term_node.tid IS NULL) GROUP BY nid ORDER BY node_data_field_list_featured_field_list_featured_value DESC, location_targeted_proximity_sort ASC

It's going through ~40 K listings nodes and finding the 30 that are closest to midtown New York. When I profile the query, it reports "Showing rows 0 - 29 (1,503 total, Query took 3.5321 sec)". The step that is dominating that time is "Copying to tmp table 3.499969".

Can you please offer any suggestions on how to get this query to take an order of magnitude less time? Is it as simple as indexing some additional columns? Is it possible to pre-calculate anything? Is the problem that the tmp table is being written to disk?

I'd greatly appreciate anything you can suggest.