Nothing. I run on windows, with hardware acceleration enabled like it is by default. Everything else is smooth and dandy.
Check and see if anyone else has this problem; if it is known; if it needs to be corrected.
When scrolling through PDFs, the scrolling is not smooth like it is in a web browser. Rather, it is pretty choppy and as a result somewhat unpleasant to look at. I love the ability to read pdfs alongside my notes (reading a study chapter while typing down notes), but my experience could be better, if the scrolling was buttery smooth.