I've found that resource is very quick when using FireFox - that's why I put the download link on the front page. Internet Explorer seems to have some really bad memory leaks and some problems displaying the map data quickly. I've gone through all the javascript, even pre-loaded the marker icons and we still have issues. So it looks like FireFox is the best browser to use for this. More on the markers soon, I'm going to organise them into colour per category and will check performance if ALL BAJR XML feeds are displayed at the same time - i.e. about 500 markers.