https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1082209554

It's down to your:
* Storage device
* CPU
* Anti-virus or other kernel-level drivers
* ISP

Pick one (or multiple).

Steam downloads and installs at the same time.

1. Downloading the encrypted and compressed chunk (Internet)
2. Decrypting and unpacking the chunk (Disk)
3. Applying the diff delta to a new copy of the patched file (Disk) [if it's a patch]
4. Deleting the previous now outdated copy of the file (Disk) [if it's a patch]

Either usage limits the other: Slower internet slows down disk progress, slow disk progress slows down chunk download.

Seem unusually slow today for me too. I have a 1 gigabit connection and had no issue downloading MK1 recently in less than an hour. There was a update for the game and it was going for a hour and I decided to uninstall the game and just re-download and it's been already been over 2 hours and i'm at 68% complete and says i'm another 1 and a half hours till download is complete.