ORBX library objects and many other payware developers products exhibit this....been an annoyance for years dating back to FSX.
Yes you can steamroll the problem with these objects by cranking AA, but I just wish developers would acknowledge it and try to correct it.
In tests I have done , default P3D objects will not exhibit the shimmering so it has to be either something with mipmaps or textures. It is almost always on smaller objects like flagpoles, lights, fences and anything thin with a metallic or reflective surface that at a far distance will resolve down to white pixels.
Also different camera views have different view settings that will cause this in external views as the focus is supposed to be on the aircraft at high detail and anything beyond that is given less graphics quality. I have seen several aircraft developers using the wrong camera definitions and I have seen the old version of EZdok using these camera settings that heighten the problem in a tradeoff for increased FPS.
If you approach anyone via support channels you always get told it's your video drivers or your settings which is total BS as I have seen this over 4 different computers 5 generations of video cards, FSX to P3D V4 and 4 operating systems .....god forbid it could be THEIR products...lol.
Edit if you are REALLY thinking I am full of it a simple search on google or youtube will show several 3D modeling videos of this same problem , it is by no means limited to FSX/P3D but it can be corrected with proper texturing and modeling.