I was reading about frame rate on the Minecraft wiki and saw this:
Increasing FPS
Disable sound effects. This is particularly effective when near a large amount of sound-producing blocks (lava, flowing water) or mobs.
I tested this myself near both lava and flowing water, and near a mob farm. I couldn't notice any difference in the framerate with sounds turned off compared to sounds turned on.
In theory, how could turning off sounds effect framerate?
Best Answer
As I said in my comment above; your main CPU has to process sounds before they're sent to the sound card for output. This takes some CPU cycles away from the processing of everything else like graphics.
Just wanted to double check before I actually provided this as an answer.