Using LR Classic CC 7.3, I've encountered a new problem. When scrolling through photos in the Develop Module, GPU Rendering will not work at either Fit or Fill zoom levels. The progress circle in the bottom right spins indefinitely. When I zoom to 1:1, 2:1, etc., the photo renders almost instantly, which is what I'm used to.
This happens for every photo, every file type. Zooming to 1:1 always fixes it.
Lightroom Classic CC 7.5 was released today and should address this issue. If you don’t see the update in your Creative Cloud App, hit the [Ctrl/Cmd]+ [Alt/Opt]+[R] to force a refresh. Give the new version a try and let us know if it solves the issue.