This does not depend on the availability of an integrated graphics card. I turned it off at the bios, but there was no result.
The game does not use all the resources available to it.
This was the case for a whole year from the release of 1.36 to the release of its latest patch. So it became again with the release of 2.0
Here is a comparison of different versions under the same conditions
GPU and fps with 2.0 - Bug Report - Warcraft III: Reforged Forums
This is still a small complaint, because ladder is played in most cases on Classic and It’s not so noticeable to them.