I'm afraid you'll have to go around and try different ones yourself, it's very hard to predict how many FPS you're going to get without having your exact setup. A good place to start looking is the shader list supplied by Optifine, you'll be able to find additional ones through google.
Also an important part is that most good shaders have internal configuration options that might allow you to get a few extra FPS while turning off some effects.
I am using a AMD R9 270X,4 Gigs of RAM and Intel core i5 1st Gen.
I'm afraid you'll have to go around and try different ones yourself, it's very hard to predict how many FPS you're going to get without having your exact setup. A good place to start looking is the shader list supplied by Optifine, you'll be able to find additional ones through google.
Also an important part is that most good shaders have internal configuration options that might allow you to get a few extra FPS while turning off some effects.
I'd say Sildur's Shaders, especially either the lite one or medium.
Discord: Ryzen_1600#7458
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Can't go wrong. Though your hardware seems lacking.