This official news post is copied verbatim from the Old School RuneScape website. It is copyrighted by Jagex.
This update was added on 12 January 2015.
This update was added on 12 January 2015.

After receiving feedback from the Old School community we have made a change to the toxic blowpipe.
In player-vs-player combat the blowpipe is now 1 tick slower. This makes it the same speed as a shortbow, which is what a large number of players felt they were voting for initially.
This change only impacts the blowpipe when it is used in player-vs-player combat. The attack speed remains the same when attacking monsters.
Mods Archie, Ash, Ghost, Ian, John C, Mat K, Reach, Ronan and Weath
The Old School team