The current 5.10.6 firmware update added a fix for flickering when auto-exposure is on, which may help to stabilize your image. The disruptive effects of gas-based lights such as fluorescent may also be reduced by running the stream at an FPS that is close to the frequency that the light is operating at. In the case of fluorescent lights, this has been 30 FPS for some people and 60 FPS for others, depending on the particular lights in their location.
If you are using IR dot pattern projection to add texture to a scene for the purposes of improving depth analysis, an external LED based IR projector may give better results than the laser-based IR projector inside the camera, especially for reducing laser speckle.
In recent discussions about IR filtering, a few users have sought to construct their own filter covers to replace the transparent material on the front of the camera casings. It is possible to buy non-reflective acrylic / perspex from companies that will cut it to size for you. An alternative is to place a micro-thin IR film over the imager lens.
The links below to these recent discussions may be useful to you.