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?