I love posts like this. First you start by saying you're a developer, as if this will now make use trust you more, along with the fact that you have clients, to make it seem like you're hot shit, and then you throw out something as stupid as this. If you're the developer, and these are your clients, and you saw that their fills are 4-6 ticks away from where they should be, you as the developer should be screaming about why. Either you're the worst developer, or this story is a lie, or you're stealing their ticks, making it seem like it has something to do with IB's fills.