Nx300- how to improve low light performance?

To begin with, I really like the NX300 and despite some of its quirks, it is capable of superb imagery with a wonderfully rich color tonality.  But to my dismay - which I'll have to find a work-around - I've discovered that high ISO pics of let's say from 2000 and above, just don't cut it with what one would expect of current day APS-C sensors.  I did a personal shoot a month or more ago in which I had little choice (very dim lighting) but to capture everything at ISO 2500 - 3200. I shot in RAW, assuming that any noise could easily be removed in Lightroom 5.3.

But converting/processing those files was one of the worst experiences I could remember when dealing with an image workflow.  Much of the noise was of such a caliber that it was difficult (sometimes impossible to remove).  I had to rely on extremely heavy Chrominance and color noise reduction - which in effect made the images look glassy (painterly effect).  I was not a happy camper and posted as much awhile back.  So now - I use the NX300 for only up to ISO 1600 - 2000.  My go-to high ISO cameras now are the Fuji X-E1 (up to ISO 6400), and the Olympus E-M5 (up to ISO 4000).

But again, you tend to learn of each camera's limitations - and they all have them.  But no, the NX300 should not be viewed as a great ISO camera.  But for everything else, I've found this camera to have a wonderful feel, let alone some gorgeous imagery.