I wouldn't generalise. Behind the scenes modern computer systems are of course processing billions of times more instructions than computers of old. Some portions of the UX do have noticeable delay and sometimes even inordinate delay. This is usually due to poor choice of algorithms and program logic, but sometimes it is the case that blazing speeds of modern hardware has trained most of us to expect every computation to be almost instant, but some algorithms are still pretty slow, no matter how fast the hardware and they are likely to remain that way. Of course the UI in particular doesn't fit into this algorithmic complexity constraint and there is little excuse for their perceptible slowness in recent years except for poor coding and feature creep.