What's up with the lag on live?

Has anyone been having trouble recently? Never used to have a problem. But forza 3, left4dead etc have been all laggy.

Left 4 Dead has been super laggy, I'm guessing it's because they are updating their servers for Left 4 Dead 2, but I don't really know. Other than that, every other game hasn't lagged one bit.

No issues here, I would look into ISP before I did Live.