not only the lagging, i experienced (and a a big number of people too) heavy slutters when im are near axis human multiengine aircrafts.
also when several enemies aircrafts are near.
the strange thing is that with the ia works fine , there are several threads about this issue. i hope they can fix it on bom or the final patch, its really a gamebreaker
http://forum.1cpublishing.eu/showthread.php?t=32222