Like I said, I just wanted you to try it and make sure (I didn't see your post about you already trying it for real tibia, ect...). But from what I have noticed it seems like if your ping is around 100-110 it will make the lag feel a lot better. Seems like 120-130+ ping is the breaking point where it stops helping as much.
Currently my ping to the server is a constant 97-99 and while using leatrix it feels almost non existent when walking with arrow keys. Without leatrix I lag step very often. However if your ping is really random say like 90-200 all over the place, then sometimes itll feel good and sometimes you will still get lag spikes.
But to be fair, saying proxy servers and TCPAckFrequency modifications are bullshit just because they don't work for you is sorta ignorant. Nobody is claiming to have 5ms latency down from 500 but the difference between something being annoying to play, and feeling quite good again is a fine line, and such modifications can help solve that issue. Also sometimes you will be routed all over random places before reaching your destination, and that's where the different proxy servers come in to try and give you a more direct route to destination.
At the end of the day, like you said all online games have servers in different regions for a reason. This ot is hosted in the best location we could to give the best ping for both usa and eu. Sorry if it does not work for you, but it is working for most people and thats the best we can do without opening 2 different servers.
Make sure you try and get to the region bosses when ppl spawn them too! They are great exp xD!
