From AIOminer Wiki

OhGodAnETHlargementPill was designed by (

The purpose is to trick your GPU's DDR5X (1080 and 1080ti) into working harder for memory heavy processes.

AIOMiner will allow for you to enable this during Ethash and Cryptonight mining. You will only see a difference if you have DDR5X memory at this time.

AIOMiner will download/installs and start/stop ETHlargementPill if you have it enabled