Just tested here ( 3ds Max 2016 SP1, GTX 780, driver 355.60 )
And it happens here too, but only in Nitrous Direct 3D 11 mode ( the default and recommended mode )
With Nitrous D3D 9 or Nitrous Software mode , it does'nt happen
There is a slight chance that it might be driver version related ( nvidia drivers from the 35x.xx branch have proven to be bug ridden, but that should have been fixed with 355.60). If it's not the driver, the cause might be some leaking OGS shader code ( on the 3ds Max side ) that is only active in the DX11 path
Anyways - someone has older, pre 35x.xx versions of nvidia drivers installed and could test/verify for the bug?
UPDATE:
Just tested in Max 2015 and i do not get the memory leak - so it seems that its really a Max 2016 SP1 ( and probably Max 2016 without SP1 ) bug. Additionally i found out that environment reflections are broken in most materials on Max 2016, in Max 2015 they work fine
Time for bug reports i guess, i'd say ...
Josef WienerroitherSoftware Developer & 3d Artist Hybrid