[2022] Why am i getting awful write speeds?

Here is what Valve has shared with us about the decryption process:

“The time it takes to decrypt the game has a large degree of variability depending on the total size of the game, the customer’s CPU capabilities, and the customer’s disk I/O speed. Customers with top-of-the line systems will likely be able to start the game within a few minutes. Customers with older/slower machines will take significantly longer.”

So it could likely be any combination of these things, unfortunately