Even though the game runs at 30-35 fps, on skirmish maps they drop below 10 and the video image freezes and unfreezes all the time making it both disturbing and unplayable. Changing vodeo options just doesn’t change anything. Has it to do anything to the map? Mission maps play normaly though with no frame drops at all.
Did you run through everything here: Warcraft III: Reforged Performance Issues - Blizzard Support?
Which mission were you playing on?
We can try to take a closer look though, please upload your system files to pastebin.com and reply with the links to the files using the preformatted text option to encapsulate the links.