jQuery UI drag/drop sorting comparision using float:left vs display:inline-block

jQuery UI drag/drop sorting comparision using float:left vs display:inline-block

I have two examples here,
only difference between these two example are
one uses display:inline-block and other one uses float:left,

li.doc_item{display:inline-block;}
 vs
li.doc_item{float:left;}

My problem is display:inline-block sorting is not as fast or responsive as float:left.
I want to use display:inline-block because thumbnails that I am re-ordering
sometimes can vary in size and float:left doesn't work well when thumbnails have different height and width.

Any question is how to make block:inline-block as fast as float:left ?

using display:inline-block
http://dev-server-2.com/drag-drop-sample/inline-block-example/

using float:left
http://dev-server-2.com/drag-drop-sample/float-example/