I bet that R7000 series card doesnt support some important effects(fog and some more) and it isnt fully DX8.1 compilant. Because of this, every Vertex operation must be done by CPU and that increases load. By lowering graphics you cant get more FPS, because LFS is not GPU intensive. It is CPU intensive and your CPU is overloaded with vertexing and it cant cope with physics calculations. Of course you can update graphic driver, but i think it will not help a lot.
I am sorry, but there is not "working" way how to seriously speed up your LFS. Integrated Graphics Processor is a limit. BTW, laptops arent considered to be a good stuff for playing.