From Halopedia, the Halo wiki
Speed Boost is a power-up enhancement featured in Halo 4, Halo 2: Anniversary and Halo 5: Guardians which drastically increases a player's movement. In addition to increasing a player's walk and run speed, it also increases the speed with which the player reloads and switches weapons, along with increasing their field of view. However, it does not increase the player's rate of fire, and the speed increase does not transfer to vehicles the player is driving. While in use, the player is awarded a visual effect which gives off a blue full-body glowing effect and leaves trails as the player moves. This effect also appears on the player's HUD, and actually increases the player's ability to see in dark conditions. In Warzone players can stack up to four speed boosts, enabling them to run at 300% normal speed.
Changes from Halo 4 to Halo 2: Anniversary
Changes from Halo 2: Anniversary to Halo 5: Guardians
Halo 5: Guardians REQ cards
List of appearances