Preview rendering is bad.

Is it just me or are there tons of artifacts on the zoomed out view in the main window?? Sometimes I am seeing really horrible square blocks around high contrast areas and also a smearing effect on certain areas of images. It's really distracting. Everything looks ok zoomed in but it still seems slightly off. The best view is the exported image though, it seems like the export and the viewport are not a 1:1. It would be great if the viewport was a little more accurate.