NHL 10 came off a year where pretty much everything worked properly at and following launch, even with the introduction of the EASHL. That has not been the case this year. Initially it was the freezing issues with the game. They may have alleviated some that were being seen after a server fix however they remain a problem for some. Now though, and seemingly more widespread, the EA Forums are littered with threads and I have received numerous accounts directly relating to severe lag online.
The NHL series is especially popular due to its online modes and performance. Having lag become a major detriment to the enjoyment being had online is something that almost certainly will be addressed and hopefully that will be done immediately. To this point there has been no statement from EA regarding the lag that so many are experiencing.