Draggable: Performance problems due to css calculations

[sorcK]

When having 200+ droppables it takes several seconds for a drag to start, and moving the draggable lags.

problem occured on ubuntu and windows vista,7 with firefox 3.5.7 , 3.6 using a highend pc

[adamffyl]

I'm having the same problem in my ASP.NET application. It's fine in any other browser but in IE8 it takes 10+ seconds to load the page just because there are so many droppables in my table. Please provide help asap.

[ghostd]

It seems (according to quick researches with firebug profiler) that a lot of time is spent in getComputedStyle: because the render of nodes is modified in many ways (adding/removins classes and changing CSS position) and _create method call'.csc('position') to check the current node position.

A first (very little) optimization could be replace the following code (from '_create' draggable method)

	(this.options.addClasses && this.element.addClass("ui-draggable"));
	(this.options.disabled && this.element.addClass("ui-draggable-disabled"));

by

	var uiClasses = this.options.addClasses ? "ui-draggable" : "";
        uiClasses += this.options.disabled ? " ui-draggable-disabled" : "";
	(uiClasses.length && this.element.addClass(uiClasses));

[mikesherov]

This ticket in core will do lots to help: ​http://bugs.jquery.com/ticket/11938