You might check out this thread below. Someone had already posted it beforehand:
Hi, I'm facing Low FPS In Warcraft Reforged Classic GFX, I'm aware that game menu is a chromium and uses on-board GPU, I'm not talking about the menu, I'm talking about the game itself Here is my specs : OS: Windows 11 Pro RAM: 16GB RAM CPU: i7 11370H GPU: RTX 3060 Monitor: 3440x1440@144HZ And...
www.hiveworkshop.com
There are numerous implications here in this thread:
1.Your CPU is not too good for handling such a resource-demanding game. In other words, it caused a serious bottlenecks if you combine such a weak CPU with stronger GPUs. Not all GPUs have the same good performance that will run such an AAA games on 1080p.
2.Before starting the game, you must make sure that Warcraft III uses the discrete GPU. In Windows 10/11, you can navigate to "Settings" -> "Display" -> "Graphics", then add the executable file for Warcraft III (located in "retail/x86_x64" folder), and make sure it's the "High Performance".
3.If the second solution won't work for you, updating the graphics card driver will solve the problem.
Also, latest Reforged patches are known for producing serious problem relating to the performance. This is due to the fact the game uses a high amount of resources to prevent memory leak-related crashes. Not to mention, playing the game on HD Mode will increase the risk of FPS drops.