Here is the full list of all 8 Jitsumi's Game Booster achievements.
Cleaned 10% or more of your memory
Cleaned 20% or more of your memory
Clean your memory for the first time
GPU Temperatures above 90C
Cleaned 30% or more of your memory
Cleaned 40% or more of your memory
Cleaned 50% or more of your memory
Use the terminal for the first time