I honestly have never touched the Multiplayer in any XCom game. The single player is all I ever needed from them.
I do know what you mean about the performance issues. But on a console, they aren't too bad. The game is fully enjoyable even with a little lag from time to time.
If my opinion means anything, i'd say it is totally worth it to revisit it. It is especially fun if you did what we used to do on here years ago. We would open a thread in the Fun Stuff section, and open up requests to be named in a players game. And they would give you updates on how your character has been doing through the campaign. I usually do this with my RL friends, so when they come over to hang out, they can enjoy the game with me a bit more.
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So, a video/audio optimization issue maybe? (On Bungie's part obviously, not your own).