I have had a problem with lag as well for about a week now. When I start playing my ping rate is around 25-40. After 5 or 6 games it starts to jump from 25-40 up to 100 and over. If I log out and wait a few minutes then log back in I am good for another 5-6 games at 25-40 ping then it starts going up again. If I keep playing it ends up between 600-700 ping. Unplayable then as the lag really makes it hard.
I have checked by equipment and it is fine and other games play with their normal ping rate. Just seems to be WOT giving me problems.