I am constantly having issues with WoW not starting when I click play. When I open my task manager I can see WoW is running but I cannot access it. It takes me several attempts to get the game to come up to where I can access it. When I do, I have multiple instances of wow running at the same time. No, I am not clicking the button multiple times.
While this is not a technical support forum, and a LONG time overdo, it’s either a Windows problem or a gfx driver problem. I’m leaning toward a driver issue since it eventually does load.
I would try launching your game from the actual directory and see if it loads quickly or also slowly.
Click the Cogwheel next to the “Play” button > Show In Explorer > Open the Highlighted folder (typically _retail_) > Open wow.exe