For Windows user running a 64 bit version of the system. If you feel adventurous you can try downloading the 32 bit version of the game with SteamCMD and check if that runs any different.

1. Download SteamCMD here: ​http://media.steampowered.com/installer/steamcmd.zip
2. Extract to any folder
3. Run steamcmd.exe
4. Type (do not include the brackets for the username/password):

   login <youruser> <yourpass>
   @sSteamCmdForcePlatformBitness 32
   force_install_dir ./7dtd/
   app_update 251570
   

5. Check if the program gave any errors during the download process. If not type exit to close it.

This will download the 32 bit version to a subfolder "7dtd" in the SteamCMD folder.

If that helps for a problem you have with the 64 bit version please report that, including what your problem with the 64 bit build was.