Fire Rate, also known as Rate of Fire (RoF) is one of 4 weapon stats that can be upgraded.
It is the speed at which weapon launches projectiles. More precisely, it is three times the number of hits per second of a weapon. So the slowest weapons, with a fire rate of 3, hit once per second, while the fastest, with a fire rate of 30, shoot 10 projectiles per second.
Machine Guns, Elementals and Submachine Guns are usually weapons with the highest fire rate. Sometimes after upgrading, a weapon gains extreme rate of fire which also increases DPS. This has the best effect on Crazy Badger, AK12/Iron Curtain, Ballers and Laser Cutter/Decimator.
Crossbow is the weapon with the lowest fire rate, because the user needs to reload the arrow each time after shooting.
Closing Time has the fastest fire rate of all shotguns, since it's fully automatic.
Hair Trigger increases fire rate of both weapons by 15%.
Equipment and Upgrades
Fire rate is the 3rd upgrade in the Workshop.
Traits and Killstreaks
RoF Boost - Gunslinger's killstreak that gives all squadmates +50% fire rate for short period of time.
Explosive Temper - Mercenary's trait that gives +25% fire rate when the hero is under 40% health.