"DPI aware" - New setting, to me personally, quite irrelevant.
The other two settings are texture related:
"Anisotropic filtering" - This will basically attempt to smooth out any shader texture applied to a world model, vehicle or skin. Some textures might not be smooth because of many factors, which could be but not limited to: something like image format but I might be wrong. More info here:
https://en.wikipedia.org/wiki/Anisotropic_filtering"Anti aliasing" - This, similar to the last one will attempt to smooth out world model textures, if you've ever been on a local server you might notice between the power lines (between lamp or power posts in the cities) a black line that "connects" them, if you've seen the texture look kind of.. blocky, anti aliasing sorts this out and will smooth out the texture to be more of a line rather than a minecraft line lol.
If you suffer from low FPS performance because of a weak GPU, both of those textures should just be left off. And even if you enable it, to me personally with a somewhat decent GPU the difference in textures is minimal or just none at all.
