Toshiba Satellite C75D-A AMD A6 lag issues

I purchased Rust on Steam yesterday when it was released and expected bountiful finds of bugs but haven’t came across any other than extreme lag. I’ve been trouble shooting the game for about two hours now with different start up commands and grass off but still only receive 20 - 30 FPS. I’ve noticed a lot of other people coming across this problem having AMD, just was curious if anyone with AMD has found a fix or so yet as I can’t find one.

Toshiba Satellite C75D-A
Processor: AMD A6 Quad-Core 2.0 GHz
Video Card: AMD Radeon HD 8400
RAM: 8GB DDR3

Game install: The game along with every other of my games is installed onto a 1TB iOmega eGO USB 3.0 external hard drive

It is a laptop issue most likely, I went and tested this on a friend’s desktop a couple days ago and he as an Athlon II processor and a GeForce GTX 660, and it was playing at a solid 60. Something about AMD mobile processors rust really doesn’t like I guess. I tried running it on my A8 laptop, and I don’t have any luck either.

I really don’t recommend this as you will have many visual artifacts but you can try the force dx level command line arguments, are you familiar with them?

I am running on a a10 4600m and 7970m, Great FPS. Just try and mess around with the start up commands to reduce graphics, I am not sure what they are but I will look around and see if I can find em.