I feel like a teenager again.

My rig has trouble running Warcraft II.

Cursor lags tremendously and the animation flips whole seconds of frames.

Operating System: Windows 10 Pro 64-bit (10.0, Build 19045) (19041.vb_release.191206-1406)
System Model: Z790 GAMING X AX
Processor: 13th Gen Intel(R) Core(TM) i9-13900KF (32 CPUs), ~3.0GHz
Memory: 65536MB RAM
Card name: AMD Radeon RX 7900 XTX
Display Memory: 57200 MB

Any idea which things to click to make it smooth?

I am having the same experience. I am stunned by what I am playing right now. I should have just kept playing my DOSbox versions which run flawlessly. I have the Battle Chest from back in 1997 and bought my first PC because of this game. I never played the BNet version of the game and didn't realize it was inferior. This GOG version has massive lag and I can't fix it. I will have to refund this. The game will be delisted and I will still have my exodos copies. I'm sure the BNet version is somewhere on the internet but if it's worse it doesn't matter. I am shocked by what I am playing right now.

PS: The "enhanced resolution controls" version is trash and runs like OP has said. The "Classic" version runs normally. I have no idea what the "enhanced" version offers. I guess you can stretch the screen and alter aspect ratio, but the experience is terrible.