Shot Speed is the attribute that governs how quickly an individual tear travels and is represented by a speeding ball. Shot Speed also affects the effective range of the tears. As the range stat determines how long tears will stay in the air (and not distance traveled), a lesser shot speed reduces effective range. Shot speed measures the velocity of each tear in contrast to the Tears stat, which measures tear frequency.
All characters start with the same shot speed except for Samson, who has a 31% increased shot speed, and Eden, whose shot speed can be anywhere between 75% and 125%.
Items that reduce shot speed cannot lower it past 0.6.
A higher shot speed will increase the directional knockback of enemies hit by the tears.
Having a high shot speed is not always desirable. While a high shot speed means enemies are easier to aim at, and effective range is increased, it also means more knockback, which can make enemies move in unpredictable ways, potentially damaging Isaac and making it harder to land consecutive shots. Some items will also directly benefit from low shot speed, such as Trisagion, Godhead, and Spoon Bender.
In co-op, Long Baby will occasionally briefly increase range, shot speed, and tear height. Dark Baby will occasionally briefly increase all stats, including shot speed.
The Era Walk card decreases shot speed and increases speed for the current room.