Severe lag in 25/40 man instances

[Nemiria]

For about two or three days, I have been experiencing severe lag inside 25 man raids and 40 man bgs. I am wondering if anyone else has experienced the same issue and if maybe someone knows the cause or any way to fix it. I know others in my guild have experienced it but only a few are affected. Any feedback would be well appreciated. Seems to be mostly NA people affected.

[skullatbash]

what is your ms usually?

And when you are in raid - 40 man Bg ?

[Criminal16]

Something happened to server a few days ago, or week ago where im lagging bad also.