I ran the latest 15.1 update to InDesign. I opened several existing file all with text and graphics (images and placed EPS files). In each file, either the text appears aliased and the graphics look ok, OR the graphics display pixelated and poo quality but the text renders correctly. Changing the "display performance" slider make no difference.

I opened a brand new document and typed in some text and imported a graphic and all displays correctly. But if i create a new file and copy and paste text and graphics from one of my previous files that does NOT display correctly, the issue are still apparent in the new document.

Here is a screen capture showing how a previous file displays in 15.1:
https://monosnap.com/file/4p8OVWmXqf2FB9QSeheRz6rfoRSgBl#sa_src=web-messaging

I have reverted to an older version and all of my files display correctly.

PC running Windows 10 - all updates have been run
32GB RAM