the lag u have could be related to the unloading of the scene. So it would only occur as an site effect.
Something interesting might be if people around u also had a d/c the same time. If so its most likely a new version of that d/c hack xtrap supposedly fixed. But cant tell much about that topic -.-". DoS attacks are not my style.
but u sayed u returned to the world list screen(my name for it
), so most likely a possible attack came form the world connection, maybe something with the whisper system. Blocking the one that tries to d/c's u. If he cant d/c u anymore, well... i would advise u to report him as a cheater then.
As for a possible fix:
there is actually very little u can do. Maybe it is because of a bug in your client, in that case reinstalling with the latest client might help.
If that does not fix your problem, chances are very slim u can do anything else about it, except trying to avoid it.