"A special machine that increases your character's speed by 5. You can only be infused once." (CURRENT DESCRIPTION)
"A special machine that infuses anyone who actives it with +3 walkspeed. You can only be infused once in total per life." (OLD DESCRIPTION)
The Speed Infuser is a Refined-tier infuser that increases a player's walkspeed by 5. It is a weaker version of the Haste Infuser.
Before the 3/31/2016 update
The Speed Infuser had the Intermediate tier, added 3 walkspeed and costed money instead of uC.