Why is World in Conflict using 97% of my GPU in the menu? As soon as i tab out to look in the task manager it stops, unless you run in windowed mode and task manager always on top then you can see it. Seems like some effort was made to hide it but at least now my PC is warming my feet playing a 17 year old game on a RTX 3060 TI while im browsing the menus?

Is GOG really up to that?

Probably not.
It's probably just a single thread, single task game brickwalling.

Use your graphics driver to put an FPS limit on your game. (Create a profile for it or use a predefined one).

Old games aren't prepared for modern graphics cards. They will happily generate 1000+ FPS in the title screen just because they can.

The game needs to be capped as others have mentioned. Also, if you have more than 8 cores there can be problems. Just read those links, and you'll probably figure it out. Also, remember to give it the old 4 GB patch which allows the program to use more than 2 gb of memory.

4 gb patch