Google Maps slow when markers on it

Question

Im writing a small webapp based on the idea of openspot for training proposal.

When I open the map with my desktop pc everything is fine, but when I open it with my HTC Desire and add a marker the map hangs.

You can find a demo here (in german)

http://park-a-lot.de

Just go to "eintragen" and set a marker. Then go hack and click on "parkplatze".

You'll see the issue.

Its ok that the toolbar at the top hides when you move the map, because of a jqtouch bug with Google maps.

Thank you in advance.