I ran into this crazy performance problem on:
- jQuery 1.7.1
- jQuery UI 1.8.16
- Twitter’s Bootstrap 1.4.0
- Windows 7 / Chrome 16.0.912.63
See how the button starts dragging from the top left corner and drags really slowly? I stripped down the CSS element by element using Chrome’s dev tools and was able to isolate the problem to the -webkit-transition and box-shadow styles on the .btn class. Setting those to none fixed the problem.