dragging content struggles when heavy markup

When the content div has lots of markup it gets very difficult to swipe to open. It's fine by clicking on the button to open the panel, but gets really heavy to open or close it by dragging. Tried to overflow hidden the content but doesn't seem to make much difference.
Any thoughts I could make it less heavy to drag?

Start by reproducing the issue with a content div containing lots of markup, comparing button opening with dragging to open or close. Investigate the drag interaction and content rendering behavior; done means dragging remains responsive with heavy markup while button opening still works.

Written by the indexing model from the issue text.