what is Anti-Aliasing ??
what is Anti-Aliasing ??
It really comes down to whether jaggies bother you. At certain settings I think AA is unnecessary, particularly with MSAA that consumes a lot of memory. The main difference is usually noticed in open-world games with big distances and many lines. The real issue is whether you feel a noticeable change when enabling or disabling it.
tldr: AA Settings Low to high -> Reduces performance (fps drop) depending on the game , But image becomes clearer as settings level is increased But frame rate drops AA off -> Game performs to the max & you might/will see image being noticeably jaggy crisp especially on the outlines , FPS will be solid to the max your GPU can handle Somewhat explained: if you've noticed jaggy edges like tiny step like textures at the on screen animation image that is known as Aliasing , AA (Anti-Aliasing)is the tech/in game setting that reduces this Jaggy edges you seen on on screen in game animation that can be a nuisance to your eyes depends on what type of gaming person you are, The variations of AA that you mentioned (MXAA , FXAA , MFAA etc) will all try to reduce this & the numbers (2x,4x,8x)are the level of smoothness you want to acheive that you can visibly feel comfortable at(it makes the same image much more smoother) , you can adjust this in an increasing order in-order to reduce the jagged image effect & the image seems more smoother & not ultra sharp crisp & jaggy on the edge when it's completely off , But this 'adjustment' relies heavily on GPU to make it work so it does so by compensating/reserving some compute power over to handle, which means the frame rates drop down to keep the image quality up , you will notice this performance difference if you have a Low entry/mid range GPU . High end GPU's usually handle it with more ease, but still the full fps bump would happen , i suggest you yourself play through same set of game play & animated cut scenes yourself with variations of AA levels , remember this is a blanket adjustment except MFAA which switches off temporarily during rapid movement on screen. so to do that GPU needs to be able to pull all that horse power or the game is light weight in that case you can play around with this on a entry/mid range GPU, So if you have a high end expensive GPU , You can pretty much play around without it affecting frame rates(more overhead) Turning it on & off : Depends on you , this is fine details . you may or may not notice it, & at the end of the day , you might not care if it's there on the screen , but on another side of things, you want quick & critical response like CSGO & some other FPS games where you rely on frame rate extremely , you want to shift things on to performance side by lowering this & other graphics settings to keep the frame rate optimal as much as possible, where as you are playing an eye candy game which requires slow & delayed response like actions in Skyrim & Tombraider you might wanna reserve the AA to an optimal point where you get to see it as a beautiful game while maintaining a smooth game play with a comfortable frame rate for you.