I've had this too .. problem seems to be this, if you're working from the example;

document.addEventListener("dragover", function (e) {
            mouseXY.x = e.clientX;
            mouseXY.y = e.clientY;
        }, false);

Not sure specifically why, but if I replace this with;

document.onmousemove = function (event) {
    this.onDragOver(event)
}.bind(this);

.. obviously I need to adapt things a little, but this provides a better solution .. replacing Vue's built-in drag handler with "vue-smooth-dnd" now yields a very smooth / performant solution.

Any updates on this one ? we're having the same problem and its freezing the browser after multiple drops