There are a great many simple fixes for increasing your Minecraft framerate. I’ve collected them here and they involve things like turning down view distance, upping the fog, using fast instead of fancy graphics.
This article assumes that you’ve done all those things. It assumes that you are currently playing on short view distance in a small window and that you’re hating your Minecraft life in the extreme.(Although even if things are not quite that dire, these mods will still help you get the best performance out of Minecraft possible.)