Let's keep in mind Irrlicht does not support DX7 rendering. It uses DX8, DX9, OGL. (Plus software rendering fall back support.)
Dx8 and especially Dx9 is faster than DX7, which is what BMax uses. So in that respect, sure there will be a speed increase.
Dx8 and especially Dx9 is faster than DX7, which is what BMax uses. So in that respect, sure there will be a speed increase.