If your game download is going more slowly than normal on the Steam client it is possible the download server you are currently using is experiencing a high volume. ( this can happen most often on big releases. )
You can check the Status of Steam Download Servers HERE.
To change the download server for your game, first click on Steam > Properties at the top of your steam window.
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in the settings menu, Go to the Downloads tab, your download server will be located just to the right. Make sure to select a region fairly close to you!
For further assistance with the Steam Client, we recommend contacting Valve’s support team HERE.