In Source Engine games, there is no lag compensation for projectiles. The lower your ping, the faster the projectile is spawned on the server. You can see this

In Source Engine games, there is no lag compensation for projectiles. The lower your ping, the faster the projectile is spawned on the server. You can see this very clearly when playing on high ping: you click mouse1, you hear the rocket fire, but the rocket doesn't appear for a good fraction of a second. Since TF2 is very heavily based around projectiles (Soldier's rockets, Demo's pills and stickies, etc) many competitive players play with their cl_interp (determines how many ticks worth of game state are delayed before being displayed, interpolated, to the player) set lower than default (which is 2 ticks at 66 ticks per second by default). This results in jerky movement if packets are lost, but it ensures that they see threats as soon as possible so that they can fire their projectiles with minimal (real time) delay. I think it might also have some effect on client side input buffering; not sure, but that would be an even bigger reason for projectile users to want low interp.