When I zoom in on a tool, it becomes blurry and has blocky stair-stepping at profile edges, also blurry. Why is this?
What size is your document, most likely cause, too small.
Options for size in Document menu. Many people have theirs at twice output size needed and render AA 1/2 size.
You’re right, that was it.
Also, if you want to get in close to your model make sure you are using Scale not Zoom. The Zoom button zooms the canvas document only, so you will see pixels at high zoom values.