Weird lag!

I'm playing on Wotlk servers i.e. Deathwing and Ragnaros. I am having a weird kind of lag.
In crowded places and bgs, I start to lag. It is weird cause I see all the other players are casting spells and moving and killing but I can not cast any spells. If I am on mount, I can not even dismount. I can move but its only visual. It is happening all the time, day and night.
I am from India and my net sucks but I didnt have this particular problem ago. I lagged but it was normal lag.
I am playing on Linux through wine.
Any advice is appriciated. Thank you.