the simple way to see if you are suffering a memory leak is checking "/showmem 1", mine nearly always stays around 730-750MB, also you could alt+tab and go to taskmanager, if you are seeing the "gameclient.exe" hit 4GB or close to that (because it's a 32bit application it can't go any more than that, even if you are running a 64bit machine (hence the "*32" next to the filename) then yes you may have a memory leak,
I personally am not, but I have suffered the framerate drop on Nukara, as I did in Tribble (which I also reported),
but the interesting thing I noted was popping into the caves reset the framerate issue for me, also I noted every time I died it got worse until I went into the caves,
so read into that what you will
/also for the record I'm running an AMD 1090t Black Edition (overclocked to 4.0Ghz), 16GB of RAM, nVidia GTX580 (1.5GB)
also, I have not been to Nukara since the new nVidia drivers came out
im not talking about game client leak here. Thats fine and for me after an hours play sits at about 1.2GB usage.
What were talking about here is a rapid drop in available video card memory availability causing frames per second to drop. Before seaosn 6 it didnt do this. Someone hasnt coded/optimised video memory usage for season 6.