By lag I mean it's not smooth, not sure if lag is a good word, I don't need to wait seconds for refresh, just milliseconds probably, but it's clearly visible wh

By lag I mean it's not smooth, not sure if lag is a good word, I don't need to wait seconds for refresh, just milliseconds probably, but it's clearly visible when I compare it to built-in Preview app (I'm using Mac) or Chrome internal pdf viewer. The smallest scroll I can make is sometimes ok, sometimes not, but normal scrolling when I'm just reading stuff is always like that, like something is blocking rendering for a moment. It was completely smooth when I started using it (~7 months ago) but I don't remember when it changed to current state. I thought that it might be some problem with Retina screen resolution and changed it to open in low resolution mode, but it didn't help.