Those settings are only meaningful for FSX and 32 bit of P3D, because they might help with OOMs, but they are completely useless on a 64 bit sim, and they might even increase stuttering, since even if they might save some memory, objects will be created and removed more often, causing more load on Simconnect and more chances of micro-stuttering.
The shadow optimization was also made for FSX and older P3D versions, which created object shadows, by projecting the airplane ( both user and AI ) over the ground so, the more complex your plane ( and AIs as well ) was, the lower the fps, so that option automatically turned off shadows over a certain altitude. This is also not required for P3D V4 and V5, because shadows are generated in a completely different way, using shaders, so the only thing affecting fps is their resolution, controlled in the sim graphic setting, which makes that option redundant.
