Just out of my curiosity, is the server lag?

For the pass few month I pay, the latency status bar in the menu showing full bar. However since min-Jan the latency always show 1bar.

Although it's 1bar, but during the in-game play still in the acceptable speed.

Anyone same as me?

Yes, I am too, although: with the average of 100 players a day, lag is bound to be worse.

It will probably get better once the new server comes in next few days.

Lag is not only caused by equipment not being powerful enough. With all the players, the bandwidth is split among everyone on the server, and that is a reason of lag (what I remember Sawine once saying on a thread 5-6 months ago).