Gmod textures randomly lower

Hello, Facepunch Support, I have had Garry’s Mod for some time now and it’s a great game. But I am having a problem with it, and I can’t seem to find any help, or knowledge on it. When I am playing on a server sometimes the textures will randomly lower, and I am talking big time lowering. There is no pattern or correlation on what causes it to lower, it just does. Despite the fact I am normally having a 40-50 FPS, it still does it anyways. I am on a MacBook pro if that helps, but if it is optimization problems, I would hope it would have been fixed.
Here is a screenshot of the same map/area, but with the textures normally, and when the drop.

Normal: https://imgur.com/a/a1xT3
When the textures randomly drop: https://imgur.com/a/kjJeq
(note) The skybox has nothing to do with the glitch.

Mac specs:
Intel core I7
500Mb’s of VRAM
8Gs of ram
512 GB SSD

i think thats your problem

try adding -dxlevel 95 on the command line parameters

Maybe you have subscribed on addon that replace textures?

I have already cleared my Gmod of all my addons, and reinstalled the ones I need (92gb’s)

[editline]24th April 2017[/editline]

I tried that, didn’t help.