Our alive missions starts with a crazy lag spike about 45 minutes into a play session. It plays perfectly up to that point and our other missions run fine throughout.

I had that not problem as well, I could play for a random amount of time and then I'd get hit but such terrible lag I actually thought the game had frozen.

I stopped MCC from loading and that issue went away. I have no idea why, but if you're using MCC give that a try.

We took MCC off our our ALiVE server and haven't seen the problem since.