Hey, I got it to work!
Here is what I did:
1. Uninstalled game completely (go into games and apps, "start"button on BF4, delete)
2. Turn off internet (Settings > Network)
3. Reinstall game from disc, should take approx. 30 min. Don't play the game while it's installing.
4. Turn on internet in settings
5. Launch game, you will be prompted to update, accept the update then wait for it to fully install.
6. Launch game, and then it was working for me! No lag, played conquest, working flawlessly.
When the internet was on, it prompts for you to update before the game installs, then takes FOREVER to install and then fails to work online. When internet is disabled, it installed MUCH FASTER.