I solved it my self - It speeds up the POS greatly over DSL network!.

In addons/point_of_sale/static/src/js/widgets.js

On line 500; change 'image' to 'image_medium':

get_image_url: function(category){ return instance.session.url('/web/binary/image', {model: 'pos.category', field: 'image_medium', id: category.id}); },

and in

addons/point_of_sale/static/src/js/models.js

Line 340; 'image' to 'image_medium':

module.Product = Backbone.Model.extend({ get_image_url: function(){ return instance.session.url('/web/binary/image', {model: 'product.product', field: 'image_medium', id: this.get('id')}); }, });