Hello there, I will buy a new rmbp 15 inch for photography (lightroom+photoshop). I will use this computer for the next 4-5 years. I am afraid of the performance of the iris pro 5200 in terms of scrolling-ui lag experienced since the beginning of the retina macbook pro. A couple posts here already mention the scrolling lag is not resolved...I don't understand why this happens... I would prefer not to spend almost 3K with the dgpu model. I will connect the macbook pro with a 27 inch display and use a scaled resolution... thank you for your input.