oh so no help :(

For the sake of repetition/length I will be referring to a few items by their slang or acronym; i.e Gun Mettle Update will be referred to as "GMU", Team Fortress 2 as TF2, and Counter Strike: Global Offensive as CS:GO.

Prior to the GMU, TF2 ran smoothly, even on its highest settings, but ever since the GMU released, TF2 stutters, not lag. The game will literally freeze every 10 or 15 seconds making the game almost unplayable and rage-inducing. Although, some freezes are shorter and much more bearable (Still very annoying), the game has not been fun to play.

I run other games such as CS:GO on fairly high settings, so it is not a problem with my computer

I have tried the following methods to fix this problem:
re-install TF2
Run TF2 on DX8
Optimize the game using the no hats mod and a config known as Chris's Config