The lag is actually quite bearable for me, so I'm guessing it's client lag.
Client lag is... difficult for me to fix. :(
For those of you experiencing severe lag issues: What sort of lag issues? Is it while clicking stuff? Does the whole interface freeze up? Or is it just in terms of the time between when you type something and when it shows up on-screen?
Pokemon Showdown | Replay player | No, I am not impressed that you know that my name is Guangcong Luo. The PS website says "Copyright Guangcong Luo" at the bottom, ffs.