I've experienced it on a few different occasions, I noticed during a test I ran Saturday, Feb 15th at 3PM EST, where there was only a handful of human players, 4-5.
During this test, there was only Luftwaffe pilots and they were having their way with the formation. As we approached the target, it began to get pretty laggy. I wondered it if it was the AI parachutes from destroyed bombers. Oddly enough, the lag was only present when I was looking East in the game.