Redmine

// Workaround for a performance regression in jQuery UI 1.12+ that makes

// sortable initialization quadratic in the number of items, freezing

// Chromium-based browsers on long lists such as custom field enumerations

// (https://github.com/jquery/jquery-ui/issues/2062).

// Collects all handles first and calls _removeClass/_addClass only once

// each, which avoids the quadratic cost while keeping the widget class

// tracking intact. Remove this override once the upstream fix lands.

if ($.ui && $.ui.sortable) {

  $.ui.sortable.prototype._setHandleClassName = function() {

    var handles = [];

    this._removeClass(

      this.element.find(".ui-sortable-handle"),

      "ui-sortable-handle"

    );

    $.each(this.items, function() {

      var handle = this.instance.options.handle;

      $.merge(handles, (handle ? this.item.find(handle) : this.item).get());

    });

    this._addClass($(handles), "ui-sortable-handle");

  };

}