So I've had this problem for a while now (since the patch, on the 22nd of May) and I really don't know how to fix this. I have really bad Lags and Freezes, mostly in dungeons since the most recent patch and shortly after the server merge. Also when I run the game via the BNS App, the game doesn't want to open, so its basically not working at all, but when I start the NC Launcher and run the game via the Launcher, it opens perfectly fine but has those massive lags and freezes instead. I tried to reinstall the game several times as well, but it didn't solve the issue for me either.
So I contacted the support and they tried to help me out, by doing an DxDiag File (general information about your pc), letting Windows search for corrupted files, updating my Intel and NVIDIA and even making a second Microsoft Account (since the old one may be corrupted). Nothing of it helped.
So yesterday evening I looked up in forums what might be the problem and I found a post about how to maybe solve the problem. To go to the BNS files and run the Client of "bin64" and "bin" as an Adminstrator, and it WORKED! BUT the next day after, it was all the same again: Lags, Freezes and the issue that I can't run via the BNS App.
Since I'm not the only one who has those issues, some people said its because of the servers? I don't know if thats the case, but when it worked for me it was 8 PM- 11 PM.