Constantly lagging, the speech is hardly ever in sync with the highlighting of the text, making it really irritating trying to follow along. I don't think there's a way to disable the highlights either. A lot of times when I'm using a premium voice it will lag so badly then start to mumble the words until they're not even words anymore. It will start to speak its own language. Really disappointing because this app could be great. Also the text is shown in a very slim box which sucks.