Thanks for your comment.
Sometimes that bothers me too. If you drag a little more slowly, the drag indicator always comes up – but of course, noone wants to “go slower” just to see that indicator.
While testing, I’ve found that Google’s Chrome browser runs way faster than even Firefox. You could give that a try.
I am planning to do some general performance enhancements over the next month and I’ll be sure to investigate drag and drop and do what I can.