Viewer pane extremely slow to load

For the last week or so my viewer pane is taking so much longer to display a pdf image. Word docs display quite quickly. Does anyone have the solution

Do you have the same problem in File Explorer?

PDF viewing is handled via the PDF viewer you have installed, not by Opus directly. If it's also slow in File Explorer, you know to look outside of Opus. Updating/repairing of changing PDF viewer will usually fix things.