Major graphics bugs on Macbook Pro 2018 (video)

Dear team,

I am using the current Steam pubvic build v.204 on Macbook Pro 2018. Specs:

13,3" Version

2,3 GHz Quad‑Core Intel Core i5 

256 GB SSD

8 GB 2133 MHz LPDDR3

Intel Iris Plus Graphics 655

MacOS High Sierra

As you can see in the video I recorded (dont mind the low resolution) the graphics is very laggy, changing resolutions or other graphics settings has no effect. 

Can you help?

Thx,

Chris

Please start at 0:30sec: