Hi. Besides lags due to new patches which is quite common until reset there maybe 2 things possible at least that have happened to me and I am prob sure you have same issues.
First you to see if your hops changed. That happened to me in the past every time around 1 week before patches and some weeks after. I sorted this out with vpn. There is free software to test how your data travels. One is called pingplotter and has free trial and the 2nd one is completely free and is called winmtr http://winmtr.net/download-winmtr/
On the host page type this account.tera.gameforge.com which is the ip address of gameforge. When you run this program let it run 2 mins or so and don't have other people use net or youtube etc cause the sample data will have interference from those.
Each line is a hop 1st line is router and last is gf server. Check on which lines you have issues. If you find out is not in the 2-3 first lines then that means its somewhere after your data left or in gf server. If issue is somewhere befor gf server then only issue to solve this is by rerouting yourself through vpn.
2nd issue that may have happened is if you don't see increased ping but feel slow is either the server lags or the fps tweaks you have had made on S1 engine may have reset. So you would need to remake those.
As I said every patch I had issues and both 2 are what has happened to me.
Sirgoulas