I have < 2meg connection, but it is quick enough on latest browsers. IE 8 is REALLY slow to both draw initial map and sometimes gives up before placing markers.
Tried ditching the xml idea and using httpRequest instead, to get the info real-time from php. It works, but the markers appear really slowly.
Each marker needs id, longitude, latitude and title.
php currently uses a session to store an array of place ids (the result of a search) and then looks up other info in mysql.