I get performance drop in stores during the playback of a video in background of goods. After the video ends, everything returns to normal. This also applies to to other videos running in background, like the one when taking goods and crew from a captured ship etc.The interface takes a while to load, if I recall. And the scrolling can be a bit slow at times as well.
But I don't think anybody ever had any major complaints about it, so I wouldn't consider this a huge priority.