sortable very slow with connectWith option on

sortable very slow with connectWith option on

Hi,

I have a ajax build web page with 10 to 15 ul-lists with up to 20 list-items each. I want to activate the sortable function with with a button. If I have the connectWith option at the sortable to connect these 10-15 lists, the activation of the sortable takes a lot of time with high cpu load and the dragging of the list-items is very laggy.
Any ideas how to speed it up?