The tab for this setting is on the rightmost section within the launcher. If you do not see tabs, they are most likely glitched, and their position is shifted down in the middle of the launcher.

This feature will reduce graphical quality when a large amount of particles are on the screen and will also reduce the texture detail of the floor based on angle (looking down at the floor is high resolution, looking parallel to the floor will load the lowest resolution)
This feature will most likely eliminate about 95% of all crashes, including area loading crashes.