Warcraft III: Reforged (Patch 1.32.9) - FPS drops too low when playing Dota map

In Reforged mode, when I play Dota map, the FPS drops too low (around 22.3) and the game is very lagging, hard to play (even I set all of settings are low and off already). Playing other maps are fine with 60 or higher FPS, only playing dota map, FPS drops and not stable.
Does anyone know how to keep FPS 60 or higher and stable when playing dota map?
Hope Blizzard can fix this issue on next patch.
Kind regards.